2 {-# OPTIONS -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 -----------------------------------------------------------------------------
17 #include "ghcconfig.h"
21 -- Forking and suchlike
22 , myThreadId -- :: IO ThreadId
23 , killThread -- :: ThreadId -> IO ()
24 , throwTo -- :: ThreadId -> Exception -> IO ()
25 , par -- :: a -> b -> b
26 , pseq -- :: a -> b -> b
28 , labelThread -- :: ThreadId -> String -> IO ()
31 , threadDelay -- :: Int -> IO ()
32 , threadWaitRead -- :: Int -> IO ()
33 , threadWaitWrite -- :: Int -> IO ()
37 , newMVar -- :: a -> IO (MVar a)
38 , newEmptyMVar -- :: IO (MVar a)
39 , takeMVar -- :: MVar a -> IO a
40 , putMVar -- :: MVar a -> a -> IO ()
41 , tryTakeMVar -- :: MVar a -> IO (Maybe a)
42 , tryPutMVar -- :: MVar a -> a -> IO Bool
43 , isEmptyMVar -- :: MVar a -> IO Bool
44 , addMVarFinalizer -- :: MVar a -> IO () -> IO ()
48 , atomically -- :: STM a -> IO a
50 , orElse -- :: STM a -> STM a -> STM a
51 , catchSTM -- :: STM a -> (Exception -> STM a) -> STM a
53 , newTVar -- :: a -> STM (TVar a)
54 , readTVar -- :: TVar a -> STM a
55 , writeTVar -- :: a -> TVar a -> STM ()
56 , unsafeIOToSTM -- :: IO a -> STM a
58 #ifdef mingw32_TARGET_OS
59 , asyncRead -- :: Int -> Int -> Int -> Ptr a -> IO (Int, Int)
60 , asyncWrite -- :: Int -> Int -> Int -> Ptr a -> IO (Int, Int)
61 , asyncDoProc -- :: FunPtr (Ptr a -> IO Int) -> Ptr a -> IO Int
63 , asyncReadBA -- :: Int -> Int -> Int -> Int -> MutableByteArray# RealWorld -> IO (Int, Int)
64 , asyncWriteBA -- :: Int -> Int -> Int -> Int -> MutableByteArray# RealWorld -> IO (Int, Int)
68 import System.Posix.Types
69 import System.Posix.Internals
77 import GHC.Num ( Num(..) )
78 import GHC.Real ( fromIntegral, quot )
79 import GHC.Base ( Int(..) )
80 import GHC.Exception ( Exception(..), AsyncException(..) )
81 import GHC.Pack ( packCString# )
82 import GHC.Ptr ( Ptr(..), plusPtr, FunPtr(..) )
85 infixr 0 `par`, `pseq`
88 %************************************************************************
90 \subsection{@ThreadId@, @par@, and @fork@}
92 %************************************************************************
95 data ThreadId = ThreadId ThreadId#
96 -- ToDo: data ThreadId = ThreadId (Weak ThreadId#)
97 -- But since ThreadId# is unlifted, the Weak type must use open
100 A 'ThreadId' is an abstract type representing a handle to a thread.
101 'ThreadId' is an instance of 'Eq', 'Ord' and 'Show', where
102 the 'Ord' instance implements an arbitrary total ordering over
103 'ThreadId's. The 'Show' instance lets you convert an arbitrary-valued
104 'ThreadId' to string form; showing a 'ThreadId' value is occasionally
105 useful when debugging or diagnosing the behaviour of a concurrent
108 /Note/: in GHC, if you have a 'ThreadId', you essentially have
109 a pointer to the thread itself. This means the thread itself can\'t be
110 garbage collected until you drop the 'ThreadId'.
111 This misfeature will hopefully be corrected at a later date.
113 /Note/: Hugs does not provide any operations on other threads;
114 it defines 'ThreadId' as a synonym for ().
117 --forkIO has now been hoisted out into the Concurrent library.
119 {- | 'killThread' terminates the given thread (GHC only).
120 Any work already done by the thread isn\'t
121 lost: the computation is suspended until required by another thread.
122 The memory used by the thread will be garbage collected if it isn\'t
123 referenced from anywhere. The 'killThread' function is defined in
126 > killThread tid = throwTo tid (AsyncException ThreadKilled)
129 killThread :: ThreadId -> IO ()
130 killThread tid = throwTo tid (AsyncException ThreadKilled)
132 {- | 'throwTo' raises an arbitrary exception in the target thread (GHC only).
134 'throwTo' does not return until the exception has been raised in the
135 target thread. The calling thread can thus be certain that the target
136 thread has received the exception. This is a useful property to know
137 when dealing with race conditions: eg. if there are two threads that
138 can kill each other, it is guaranteed that only one of the threads
139 will get to kill the other. -}
140 throwTo :: ThreadId -> Exception -> IO ()
141 throwTo (ThreadId id) ex = IO $ \ s ->
142 case (killThread# id ex s) of s1 -> (# s1, () #)
144 -- | Returns the 'ThreadId' of the calling thread (GHC only).
145 myThreadId :: IO ThreadId
146 myThreadId = IO $ \s ->
147 case (myThreadId# s) of (# s1, id #) -> (# s1, ThreadId id #)
150 -- |The 'yield' action allows (forces, in a co-operative multitasking
151 -- implementation) a context-switch to any other currently runnable
152 -- threads (if any), and is occasionally useful when implementing
153 -- concurrency abstractions.
156 case (yield# s) of s1 -> (# s1, () #)
158 {- | 'labelThread' stores a string as identifier for this thread if
159 you built a RTS with debugging support. This identifier will be used in
160 the debugging output to make distinction of different threads easier
161 (otherwise you only have the thread state object\'s address in the heap).
163 Other applications like the graphical Concurrent Haskell Debugger
164 (<http://www.informatik.uni-kiel.de/~fhu/chd/>) may choose to overload
165 'labelThread' for their purposes as well.
168 labelThread :: ThreadId -> String -> IO ()
169 labelThread (ThreadId t) str = IO $ \ s ->
170 let ps = packCString# str
171 adr = byteArrayContents# ps in
172 case (labelThread# t adr s) of s1 -> (# s1, () #)
174 -- Nota Bene: 'pseq' used to be 'seq'
175 -- but 'seq' is now defined in PrelGHC
177 -- "pseq" is defined a bit weirdly (see below)
179 -- The reason for the strange "lazy" call is that
180 -- it fools the compiler into thinking that pseq and par are non-strict in
181 -- their second argument (even if it inlines pseq at the call site).
182 -- If it thinks pseq is strict in "y", then it often evaluates
183 -- "y" before "x", which is totally wrong.
187 pseq x y = x `seq` lazy y
191 par x y = case (par# x) of { _ -> lazy y }
195 %************************************************************************
197 \subsection[stm]{Transactional heap operations}
199 %************************************************************************
201 TVars are shared memory locations which support atomic memory
205 newtype STM a = STM (State# RealWorld -> (# State# RealWorld, a #))
207 unSTM :: STM a -> (State# RealWorld -> (# State# RealWorld, a #))
210 instance Functor STM where
211 fmap f x = x >>= (return . f)
213 instance Monad STM where
214 {-# INLINE return #-}
218 return x = returnSTM x
219 m >>= k = bindSTM m k
221 bindSTM :: STM a -> (a -> STM b) -> STM b
222 bindSTM (STM m) k = STM ( \s ->
224 (# new_s, a #) -> unSTM (k a) new_s
227 thenSTM :: STM a -> STM b -> STM b
228 thenSTM (STM m) k = STM ( \s ->
230 (# new_s, a #) -> unSTM k new_s
233 returnSTM :: a -> STM a
234 returnSTM x = STM (\s -> (# s, x #))
236 -- | Unsafely performs IO in the STM monad.
237 unsafeIOToSTM :: IO a -> STM a
238 unsafeIOToSTM (IO m) = STM m
240 -- |Perform a series of STM actions atomically.
241 atomically :: STM a -> IO a
242 atomically (STM m) = IO (\s -> (atomically# m) s )
244 -- |Retry execution of the current memory transaction because it has seen
245 -- values in TVars which mean that it should not continue (e.g. the TVars
246 -- represent a shared buffer that is now empty). The implementation may
247 -- block the thread until one of the TVars that it has read from has been
250 retry = STM $ \s# -> retry# s#
252 -- |Compose two alternative STM actions. If the first action completes without
253 -- retrying then it forms the result of the orElse. Otherwise, if the first
254 -- action retries, then the second action is tried in its place. If both actions
255 -- retry then the orElse as a whole retries.
256 orElse :: STM a -> STM a -> STM a
257 orElse (STM m) e = STM $ \s -> catchRetry# m (unSTM e) s
259 -- |Exception handling within STM actions.
260 catchSTM :: STM a -> (Exception -> STM a) -> STM a
261 catchSTM (STM m) k = STM $ \s -> catchSTM# m (\ex -> unSTM (k ex)) s
263 data TVar a = TVar (TVar# RealWorld a)
265 instance Eq (TVar a) where
266 (TVar tvar1#) == (TVar tvar2#) = sameTVar# tvar1# tvar2#
268 -- |Create a new TVar holding a value supplied
269 newTVar :: a -> STM (TVar a)
270 newTVar val = STM $ \s1# ->
271 case newTVar# val s1# of
272 (# s2#, tvar# #) -> (# s2#, TVar tvar# #)
274 -- |Return the current value stored in a TVar
275 readTVar :: TVar a -> STM a
276 readTVar (TVar tvar#) = STM $ \s# -> readTVar# tvar# s#
278 -- |Write the supplied value into a TVar
279 writeTVar :: TVar a -> a -> STM ()
280 writeTVar (TVar tvar#) val = STM $ \s1# ->
281 case writeTVar# tvar# val s1# of
286 %************************************************************************
288 \subsection[mvars]{M-Structures}
290 %************************************************************************
292 M-Vars are rendezvous points for concurrent threads. They begin
293 empty, and any attempt to read an empty M-Var blocks. When an M-Var
294 is written, a single blocked thread may be freed. Reading an M-Var
295 toggles its state from full back to empty. Therefore, any value
296 written to an M-Var may only be read once. Multiple reads and writes
297 are allowed, but there must be at least one read between any two
301 --Defined in IOBase to avoid cycle: data MVar a = MVar (SynchVar# RealWorld a)
303 -- |Create an 'MVar' which is initially empty.
304 newEmptyMVar :: IO (MVar a)
305 newEmptyMVar = IO $ \ s# ->
307 (# s2#, svar# #) -> (# s2#, MVar svar# #)
309 -- |Create an 'MVar' which contains the supplied value.
310 newMVar :: a -> IO (MVar a)
312 newEmptyMVar >>= \ mvar ->
313 putMVar mvar value >>
316 -- |Return the contents of the 'MVar'. If the 'MVar' is currently
317 -- empty, 'takeMVar' will wait until it is full. After a 'takeMVar',
318 -- the 'MVar' is left empty.
320 -- If several threads are competing to take the same 'MVar', one is chosen
321 -- to continue at random when the 'MVar' becomes full.
322 takeMVar :: MVar a -> IO a
323 takeMVar (MVar mvar#) = IO $ \ s# -> takeMVar# mvar# s#
325 -- |Put a value into an 'MVar'. If the 'MVar' is currently full,
326 -- 'putMVar' will wait until it becomes empty.
328 -- If several threads are competing to fill the same 'MVar', one is
329 -- chosen to continue at random when the 'MVar' becomes empty.
330 putMVar :: MVar a -> a -> IO ()
331 putMVar (MVar mvar#) x = IO $ \ s# ->
332 case putMVar# mvar# x s# of
335 -- |A non-blocking version of 'takeMVar'. The 'tryTakeMVar' function
336 -- returns immediately, with 'Nothing' if the 'MVar' was empty, or
337 -- @'Just' a@ if the 'MVar' was full with contents @a@. After 'tryTakeMVar',
338 -- the 'MVar' is left empty.
339 tryTakeMVar :: MVar a -> IO (Maybe a)
340 tryTakeMVar (MVar m) = IO $ \ s ->
341 case tryTakeMVar# m s of
342 (# s, 0#, _ #) -> (# s, Nothing #) -- MVar is empty
343 (# s, _, a #) -> (# s, Just a #) -- MVar is full
345 -- |A non-blocking version of 'putMVar'. The 'tryPutMVar' function
346 -- attempts to put the value @a@ into the 'MVar', returning 'True' if
347 -- it was successful, or 'False' otherwise.
348 tryPutMVar :: MVar a -> a -> IO Bool
349 tryPutMVar (MVar mvar#) x = IO $ \ s# ->
350 case tryPutMVar# mvar# x s# of
351 (# s, 0# #) -> (# s, False #)
352 (# s, _ #) -> (# s, True #)
354 -- |Check whether a given 'MVar' is empty.
356 -- Notice that the boolean value returned is just a snapshot of
357 -- the state of the MVar. By the time you get to react on its result,
358 -- the MVar may have been filled (or emptied) - so be extremely
359 -- careful when using this operation. Use 'tryTakeMVar' instead if possible.
360 isEmptyMVar :: MVar a -> IO Bool
361 isEmptyMVar (MVar mv#) = IO $ \ s# ->
362 case isEmptyMVar# mv# s# of
363 (# s2#, flg #) -> (# s2#, not (flg ==# 0#) #)
365 -- |Add a finalizer to an 'MVar' (GHC only). See "Foreign.ForeignPtr" and
366 -- "System.Mem.Weak" for more about finalizers.
367 addMVarFinalizer :: MVar a -> IO () -> IO ()
368 addMVarFinalizer (MVar m) finalizer =
369 IO $ \s -> case mkWeak# m () finalizer s of { (# s1, w #) -> (# s1, () #) }
373 %************************************************************************
375 \subsection{Thread waiting}
377 %************************************************************************
380 #ifdef mingw32_TARGET_OS
382 -- Note: threadDelay, threadWaitRead and threadWaitWrite aren't really functional
383 -- on Win32, but left in there because lib code (still) uses them (the manner
384 -- in which they're used doesn't cause problems on a Win32 platform though.)
386 asyncRead :: Int -> Int -> Int -> Ptr a -> IO (Int, Int)
387 asyncRead (I# fd) (I# isSock) (I# len) (Ptr buf) = do
388 (l, rc) <- IO (\s -> case asyncRead# fd isSock len buf s of
389 (# s, len#, err# #) -> (# s, (I# len#, I# err#) #))
390 -- special handling for Ctrl+C-aborted 'standard input' reads;
391 -- see rts/win32/ConsoleHandler.c for details.
392 if (l == 0 && rc == -2)
393 then asyncRead (I# fd) (I# isSock) (I# len) (Ptr buf)
396 asyncWrite :: Int -> Int -> Int -> Ptr a -> IO (Int, Int)
397 asyncWrite (I# fd) (I# isSock) (I# len) (Ptr buf) =
398 IO $ \s -> case asyncWrite# fd isSock len buf s of
399 (# s, len#, err# #) -> (# s, (I# len#, I# err#) #)
401 asyncDoProc :: FunPtr (Ptr a -> IO Int) -> Ptr a -> IO Int
402 asyncDoProc (FunPtr proc) (Ptr param) =
403 -- the 'length' value is ignored; simplifies implementation of
404 -- the async*# primops to have them all return the same result.
405 IO $ \s -> case asyncDoProc# proc param s of
406 (# s, len#, err# #) -> (# s, I# err# #)
408 -- to aid the use of these primops by the IO Handle implementation,
409 -- provide the following convenience funs:
411 -- this better be a pinned byte array!
412 asyncReadBA :: Int -> Int -> Int -> Int -> MutableByteArray# RealWorld -> IO (Int,Int)
413 asyncReadBA fd isSock len off bufB =
414 asyncRead fd isSock len ((Ptr (byteArrayContents# (unsafeCoerce# bufB))) `plusPtr` off)
416 asyncWriteBA :: Int -> Int -> Int -> Int -> MutableByteArray# RealWorld -> IO (Int,Int)
417 asyncWriteBA fd isSock len off bufB =
418 asyncWrite fd isSock len ((Ptr (byteArrayContents# (unsafeCoerce# bufB))) `plusPtr` off)
422 -- -----------------------------------------------------------------------------
425 -- | Block the current thread until data is available to read on the
426 -- given file descriptor (GHC only).
427 threadWaitRead :: Fd -> IO ()
429 #ifndef mingw32_TARGET_OS
430 | threaded = waitForReadEvent fd
432 | otherwise = IO $ \s ->
433 case fromIntegral fd of { I# fd# ->
434 case waitRead# fd# s of { s -> (# s, () #)
437 -- | Block the current thread until data can be written to the
438 -- given file descriptor (GHC only).
439 threadWaitWrite :: Fd -> IO ()
441 #ifndef mingw32_TARGET_OS
442 | threaded = waitForWriteEvent fd
444 | otherwise = IO $ \s ->
445 case fromIntegral fd of { I# fd# ->
446 case waitWrite# fd# s of { s -> (# s, () #)
449 -- | Suspends the current thread for a given number of microseconds
452 -- Note that the resolution used by the Haskell runtime system's
453 -- internal timer is 1\/50 second, and 'threadDelay' will round its
454 -- argument up to the nearest multiple of this resolution.
456 -- There is no guarantee that the thread will be rescheduled promptly
457 -- when the delay has expired, but the thread will never continue to
458 -- run /earlier/ than specified.
460 threadDelay :: Int -> IO ()
462 #ifndef mingw32_TARGET_OS
463 | threaded = waitForDelayEvent time
465 | threaded = c_Sleep (fromIntegral (time `quot` 1000))
467 | otherwise = IO $ \s ->
468 case fromIntegral time of { I# time# ->
469 case delay# time# s of { s -> (# s, () #)
472 -- On Windows, we just make a safe call to 'Sleep' to implement threadDelay.
473 #ifdef mingw32_TARGET_OS
474 foreign import ccall safe "Sleep" c_Sleep :: CInt -> IO ()
477 foreign import ccall unsafe "rtsSupportsBoundThreads" threaded :: Bool
479 -- ----------------------------------------------------------------------------
480 -- Threaded RTS implementation of threadWaitRead, threadWaitWrite, threadDelay
482 -- In the threaded RTS, we employ a single IO Manager thread to wait
483 -- for all outstanding IO requests (threadWaitRead,threadWaitWrite)
484 -- and delays (threadDelay).
486 -- We can do this because in the threaded RTS the IO Manager can make
487 -- a non-blocking call to select(), so we don't have to do select() in
488 -- the scheduler as we have to in the non-threaded RTS. We get performance
489 -- benefits from doing it this way, because we only have to restart the select()
490 -- when a new request arrives, rather than doing one select() each time
491 -- around the scheduler loop. Furthermore, the scheduler can be simplified
492 -- by not having to check for completed IO requests.
494 -- Issues, possible problems:
496 -- - we might want bound threads to just do the blocking
497 -- operation rather than communicating with the IO manager
498 -- thread. This would prevent simgle-threaded programs which do
499 -- IO from requiring multiple OS threads. However, it would also
500 -- prevent bound threads waiting on IO from being killed or sent
503 -- - Apprently exec() doesn't work on Linux in a multithreaded program.
504 -- I couldn't repeat this.
506 -- - How do we handle signal delivery in the multithreaded RTS?
508 -- - forkProcess will kill the IO manager thread. Let's just
509 -- hope we don't need to do any blocking IO between fork & exec.
511 #ifndef mingw32_TARGET_OS
514 = Read {-# UNPACK #-} !Fd {-# UNPACK #-} !(MVar ())
515 | Write {-# UNPACK #-} !Fd {-# UNPACK #-} !(MVar ())
518 = Delay {-# UNPACK #-} !Int {-# UNPACK #-} !(MVar ())
520 pendingEvents :: IORef [IOReq]
521 pendingDelays :: IORef [DelayReq]
522 -- could use a strict list or array here
523 {-# NOINLINE pendingEvents #-}
524 {-# NOINLINE pendingDelays #-}
525 (pendingEvents,pendingDelays) = unsafePerformIO $ do
530 -- the first time we schedule an IO request, the service thread
531 -- will be created (cool, huh?)
533 startIOServiceThread :: IO ()
534 startIOServiceThread = do
535 allocaArray 2 $ \fds -> do
536 throwErrnoIfMinus1 "startIOServiceThread" (c_pipe fds)
537 rd_end <- peekElemOff fds 0
538 wr_end <- peekElemOff fds 1
539 writeIORef stick (fromIntegral wr_end)
541 allocaBytes sizeofFdSet $ \readfds -> do
542 allocaBytes sizeofFdSet $ \writefds -> do
543 allocaBytes sizeofTimeVal $ \timeval -> do
544 service_loop (fromIntegral rd_end) readfds writefds timeval [] []
547 -- XXX: move real forkIO here from Control.Concurrent?
548 quickForkIO action = IO $ \s ->
549 case (fork# action s) of (# s1, id #) -> (# s1, ThreadId id #)
552 :: Fd -- listen to this for wakeup calls
559 service_loop wakeup readfds writefds ptimeval old_reqs old_delays = do
561 -- pick up new IO requests
562 new_reqs <- atomicModifyIORef pendingEvents (\a -> ([],a))
563 let reqs = new_reqs ++ old_reqs
565 -- pick up new delay requests
566 new_delays <- atomicModifyIORef pendingDelays (\a -> ([],a))
567 let delays = foldr insertDelay old_delays new_delays
569 -- build the FDSets for select()
573 maxfd <- buildFdSets 0 readfds writefds reqs
575 -- check the current time and wake up any thread in threadDelay whose
576 -- timeout has expired. Also find the timeout value for the select() call.
578 (delays', timeout) <- getDelay now ptimeval delays
580 -- perform the select()
582 res <- c_select ((max wakeup maxfd)+1) readfds writefds
593 -- ToDo: check result
595 b <- takeMVar prodding
596 if b then alloca $ \p -> do c_read (fromIntegral wakeup) p 1; return ()
598 putMVar prodding False
600 reqs' <- completeRequests reqs readfds writefds []
601 service_loop wakeup readfds writefds ptimeval reqs' delays'
604 {-# NOINLINE stick #-}
605 stick = unsafePerformIO (newIORef 0)
607 prodding :: MVar Bool
608 {-# NOINLINE prodding #-}
609 prodding = unsafePerformIO (newMVar False)
611 prodServiceThread :: IO ()
612 prodServiceThread = do
613 b <- takeMVar prodding
615 then do fd <- readIORef stick
616 with 42 $ \pbuf -> do c_write (fromIntegral fd) pbuf 1; return ()
618 putMVar prodding True
620 -- -----------------------------------------------------------------------------
623 buildFdSets maxfd readfds writefds [] = return maxfd
624 buildFdSets maxfd readfds writefds (Read fd m : reqs) = do
626 buildFdSets (max maxfd fd) readfds writefds reqs
627 buildFdSets maxfd readfds writefds (Write fd m : reqs) = do
629 buildFdSets (max maxfd fd) readfds writefds reqs
631 completeRequests [] _ _ reqs' = return reqs'
632 completeRequests (Read fd m : reqs) readfds writefds reqs' = do
633 b <- fdIsSet fd readfds
635 then do putMVar m (); completeRequests reqs readfds writefds reqs'
636 else completeRequests reqs readfds writefds (Read fd m : reqs')
637 completeRequests (Write fd m : reqs) readfds writefds reqs' = do
638 b <- fdIsSet fd writefds
640 then do putMVar m (); completeRequests reqs readfds writefds reqs'
641 else completeRequests reqs readfds writefds (Write fd m : reqs')
643 waitForReadEvent :: Fd -> IO ()
644 waitForReadEvent fd = do
646 atomicModifyIORef pendingEvents (\xs -> (Read fd m : xs, ()))
650 waitForWriteEvent :: Fd -> IO ()
651 waitForWriteEvent fd = do
653 atomicModifyIORef pendingEvents (\xs -> (Write fd m : xs, ()))
657 -- XXX: move into GHC.IOBase from Data.IORef?
658 atomicModifyIORef :: IORef a -> (a -> (a,b)) -> IO b
659 atomicModifyIORef (IORef (STRef r#)) f = IO $ \s -> atomicModifyMutVar# r# f s
661 -- -----------------------------------------------------------------------------
664 waitForDelayEvent :: Int -> IO ()
665 waitForDelayEvent usecs = do
668 let target = now + usecs `quot` tick_usecs
669 atomicModifyIORef pendingDelays (\xs -> (Delay target m : xs, ()))
673 -- Walk the queue of pending delays, waking up any that have passed
674 -- and return the smallest delay to wait for. The queue of pending
675 -- delays is kept ordered.
676 getDelay :: Ticks -> Ptr CTimeVal -> [DelayReq] -> IO ([DelayReq], Ptr CTimeVal)
677 getDelay now ptimeval [] = return ([],nullPtr)
678 getDelay now ptimeval all@(Delay time m : rest)
681 getDelay now ptimeval rest
683 setTimevalTicks ptimeval (time - now)
684 return (all,ptimeval)
686 insertDelay :: DelayReq -> [DelayReq] -> [DelayReq]
687 insertDelay d@(Delay time m) [] = [d]
688 insertDelay d1@(Delay time m) ds@(d2@(Delay time' m') : rest)
689 | time <= time' = d1 : ds
690 | otherwise = d2 : insertDelay d1 rest
693 tick_freq = 50 :: Ticks -- accuracy of threadDelay (ticks per sec)
694 tick_usecs = 1000000 `quot` tick_freq :: Int
696 newtype CTimeVal = CTimeVal ()
698 foreign import ccall unsafe "sizeofTimeVal"
701 foreign import ccall unsafe "getTicksOfDay"
702 getTicksOfDay :: IO Ticks
704 foreign import ccall unsafe "setTimevalTicks"
705 setTimevalTicks :: Ptr CTimeVal -> Ticks -> IO ()
707 -- ----------------------------------------------------------------------------
708 -- select() interface
710 -- ToDo: move to System.Posix.Internals?
712 newtype CFdSet = CFdSet ()
714 foreign import ccall safe "select"
715 c_select :: Fd -> Ptr CFdSet -> Ptr CFdSet -> Ptr CFdSet -> Ptr CTimeVal
718 foreign import ccall unsafe "hsFD_CLR"
719 fdClr :: Fd -> Ptr CFdSet -> IO ()
721 foreign import ccall unsafe "hsFD_ISSET"
722 fdIsSet :: Fd -> Ptr CFdSet -> IO CInt
724 foreign import ccall unsafe "hsFD_SET"
725 fdSet :: Fd -> Ptr CFdSet -> IO ()
727 foreign import ccall unsafe "hsFD_ZERO"
728 fdZero :: Ptr CFdSet -> IO ()
730 foreign import ccall unsafe "sizeof_fd_set"