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 -----------------------------------------------------------------------------
17 -- No: #hide, because bits of this module are exposed by the stm package.
22 -- Forking and suchlike
23 , myThreadId -- :: IO ThreadId
24 , killThread -- :: ThreadId -> IO ()
25 , throwTo -- :: ThreadId -> Exception -> IO ()
26 , par -- :: a -> b -> b
27 , pseq -- :: a -> b -> b
29 , labelThread -- :: ThreadId -> String -> IO ()
32 , threadDelay -- :: Int -> IO ()
33 , threadWaitRead -- :: Int -> IO ()
34 , threadWaitWrite -- :: Int -> IO ()
38 , newMVar -- :: a -> IO (MVar a)
39 , newEmptyMVar -- :: IO (MVar a)
40 , takeMVar -- :: MVar a -> IO a
41 , putMVar -- :: MVar a -> a -> IO ()
42 , tryTakeMVar -- :: MVar a -> IO (Maybe a)
43 , tryPutMVar -- :: MVar a -> a -> IO Bool
44 , isEmptyMVar -- :: MVar a -> IO Bool
45 , addMVarFinalizer -- :: MVar a -> IO () -> IO ()
49 , atomically -- :: STM a -> IO a
51 , orElse -- :: STM a -> STM a -> STM a
52 , catchSTM -- :: STM a -> (Exception -> STM a) -> STM a
54 , newTVar -- :: a -> STM (TVar a)
55 , readTVar -- :: TVar a -> STM a
56 , writeTVar -- :: a -> TVar a -> STM ()
57 , unsafeIOToSTM -- :: IO a -> STM a
59 #ifdef mingw32_HOST_OS
60 , asyncRead -- :: Int -> Int -> Int -> Ptr a -> IO (Int, Int)
61 , asyncWrite -- :: Int -> Int -> Int -> Ptr a -> IO (Int, Int)
62 , asyncDoProc -- :: FunPtr (Ptr a -> IO Int) -> Ptr a -> IO Int
64 , asyncReadBA -- :: Int -> Int -> Int -> Int -> MutableByteArray# RealWorld -> IO (Int, Int)
65 , asyncWriteBA -- :: Int -> Int -> Int -> Int -> MutableByteArray# RealWorld -> IO (Int, Int)
69 import System.Posix.Types
70 import System.Posix.Internals
78 import GHC.Num ( Num(..) )
79 import GHC.Real ( fromIntegral, quot )
80 import GHC.Base ( Int(..) )
81 import GHC.Exception ( Exception(..), AsyncException(..) )
82 import GHC.Pack ( packCString# )
83 import GHC.Ptr ( Ptr(..), plusPtr, FunPtr(..) )
87 infixr 0 `par`, `pseq`
90 %************************************************************************
92 \subsection{@ThreadId@, @par@, and @fork@}
94 %************************************************************************
97 data ThreadId = ThreadId ThreadId# deriving( Typeable )
98 -- ToDo: data ThreadId = ThreadId (Weak ThreadId#)
99 -- But since ThreadId# is unlifted, the Weak type must use open
102 A 'ThreadId' is an abstract type representing a handle to a thread.
103 'ThreadId' is an instance of 'Eq', 'Ord' and 'Show', where
104 the 'Ord' instance implements an arbitrary total ordering over
105 'ThreadId's. The 'Show' instance lets you convert an arbitrary-valued
106 'ThreadId' to string form; showing a 'ThreadId' value is occasionally
107 useful when debugging or diagnosing the behaviour of a concurrent
110 /Note/: in GHC, if you have a 'ThreadId', you essentially have
111 a pointer to the thread itself. This means the thread itself can\'t be
112 garbage collected until you drop the 'ThreadId'.
113 This misfeature will hopefully be corrected at a later date.
115 /Note/: Hugs does not provide any operations on other threads;
116 it defines 'ThreadId' as a synonym for ().
119 --forkIO has now been hoisted out into the Concurrent library.
121 {- | 'killThread' terminates the given thread (GHC only).
122 Any work already done by the thread isn\'t
123 lost: the computation is suspended until required by another thread.
124 The memory used by the thread will be garbage collected if it isn\'t
125 referenced from anywhere. The 'killThread' function is defined in
128 > killThread tid = throwTo tid (AsyncException ThreadKilled)
131 killThread :: ThreadId -> IO ()
132 killThread tid = throwTo tid (AsyncException ThreadKilled)
134 {- | 'throwTo' raises an arbitrary exception in the target thread (GHC only).
136 'throwTo' does not return until the exception has been raised in the
137 target thread. The calling thread can thus be certain that the target
138 thread has received the exception. This is a useful property to know
139 when dealing with race conditions: eg. if there are two threads that
140 can kill each other, it is guaranteed that only one of the threads
141 will get to kill the other. -}
142 throwTo :: ThreadId -> Exception -> IO ()
143 throwTo (ThreadId id) ex = IO $ \ s ->
144 case (killThread# id ex s) of s1 -> (# s1, () #)
146 -- | Returns the 'ThreadId' of the calling thread (GHC only).
147 myThreadId :: IO ThreadId
148 myThreadId = IO $ \s ->
149 case (myThreadId# s) of (# s1, id #) -> (# s1, ThreadId id #)
152 -- |The 'yield' action allows (forces, in a co-operative multitasking
153 -- implementation) a context-switch to any other currently runnable
154 -- threads (if any), and is occasionally useful when implementing
155 -- concurrency abstractions.
158 case (yield# s) of s1 -> (# s1, () #)
160 {- | 'labelThread' stores a string as identifier for this thread if
161 you built a RTS with debugging support. This identifier will be used in
162 the debugging output to make distinction of different threads easier
163 (otherwise you only have the thread state object\'s address in the heap).
165 Other applications like the graphical Concurrent Haskell Debugger
166 (<http://www.informatik.uni-kiel.de/~fhu/chd/>) may choose to overload
167 'labelThread' for their purposes as well.
170 labelThread :: ThreadId -> String -> IO ()
171 labelThread (ThreadId t) str = IO $ \ s ->
172 let ps = packCString# str
173 adr = byteArrayContents# ps in
174 case (labelThread# t adr s) of s1 -> (# s1, () #)
176 -- Nota Bene: 'pseq' used to be 'seq'
177 -- but 'seq' is now defined in PrelGHC
179 -- "pseq" is defined a bit weirdly (see below)
181 -- The reason for the strange "lazy" call is that
182 -- it fools the compiler into thinking that pseq and par are non-strict in
183 -- their second argument (even if it inlines pseq at the call site).
184 -- If it thinks pseq is strict in "y", then it often evaluates
185 -- "y" before "x", which is totally wrong.
189 pseq x y = x `seq` lazy y
193 par x y = case (par# x) of { _ -> lazy y }
197 %************************************************************************
199 \subsection[stm]{Transactional heap operations}
201 %************************************************************************
203 TVars are shared memory locations which support atomic memory
207 newtype STM a = STM (State# RealWorld -> (# State# RealWorld, a #)) deriving( Typeable )
209 unSTM :: STM a -> (State# RealWorld -> (# State# RealWorld, a #))
212 instance Functor STM where
213 fmap f x = x >>= (return . f)
215 instance Monad STM where
216 {-# INLINE return #-}
220 return x = returnSTM x
221 m >>= k = bindSTM m k
223 bindSTM :: STM a -> (a -> STM b) -> STM b
224 bindSTM (STM m) k = STM ( \s ->
226 (# new_s, a #) -> unSTM (k a) new_s
229 thenSTM :: STM a -> STM b -> STM b
230 thenSTM (STM m) k = STM ( \s ->
232 (# new_s, a #) -> unSTM k new_s
235 returnSTM :: a -> STM a
236 returnSTM x = STM (\s -> (# s, x #))
238 -- | Unsafely performs IO in the STM monad.
239 unsafeIOToSTM :: IO a -> STM a
240 unsafeIOToSTM (IO m) = STM m
242 -- |Perform a series of STM actions atomically.
243 atomically :: STM a -> IO a
244 atomically (STM m) = IO (\s -> (atomically# m) s )
246 -- |Retry execution of the current memory transaction because it has seen
247 -- values in TVars which mean that it should not continue (e.g. the TVars
248 -- represent a shared buffer that is now empty). The implementation may
249 -- block the thread until one of the TVars that it has read from has been
252 retry = STM $ \s# -> retry# s#
254 -- |Compose two alternative STM actions. If the first action completes without
255 -- retrying then it forms the result of the orElse. Otherwise, if the first
256 -- action retries, then the second action is tried in its place. If both actions
257 -- retry then the orElse as a whole retries.
258 orElse :: STM a -> STM a -> STM a
259 orElse (STM m) e = STM $ \s -> catchRetry# m (unSTM e) s
261 -- |Exception handling within STM actions.
262 catchSTM :: STM a -> (Exception -> STM a) -> STM a
263 catchSTM (STM m) k = STM $ \s -> catchSTM# m (\ex -> unSTM (k ex)) s
265 data TVar a = TVar (TVar# RealWorld a) deriving( Typeable )
267 instance Eq (TVar a) where
268 (TVar tvar1#) == (TVar tvar2#) = sameTVar# tvar1# tvar2#
270 -- |Create a new TVar holding a value supplied
271 newTVar :: a -> STM (TVar a)
272 newTVar val = STM $ \s1# ->
273 case newTVar# val s1# of
274 (# s2#, tvar# #) -> (# s2#, TVar tvar# #)
276 -- |Return the current value stored in a TVar
277 readTVar :: TVar a -> STM a
278 readTVar (TVar tvar#) = STM $ \s# -> readTVar# tvar# s#
280 -- |Write the supplied value into a TVar
281 writeTVar :: TVar a -> a -> STM ()
282 writeTVar (TVar tvar#) val = STM $ \s1# ->
283 case writeTVar# tvar# val s1# of
288 %************************************************************************
290 \subsection[mvars]{M-Structures}
292 %************************************************************************
294 M-Vars are rendezvous points for concurrent threads. They begin
295 empty, and any attempt to read an empty M-Var blocks. When an M-Var
296 is written, a single blocked thread may be freed. Reading an M-Var
297 toggles its state from full back to empty. Therefore, any value
298 written to an M-Var may only be read once. Multiple reads and writes
299 are allowed, but there must be at least one read between any two
303 --Defined in IOBase to avoid cycle: data MVar a = MVar (SynchVar# RealWorld a)
305 -- |Create an 'MVar' which is initially empty.
306 newEmptyMVar :: IO (MVar a)
307 newEmptyMVar = IO $ \ s# ->
309 (# s2#, svar# #) -> (# s2#, MVar svar# #)
311 -- |Create an 'MVar' which contains the supplied value.
312 newMVar :: a -> IO (MVar a)
314 newEmptyMVar >>= \ mvar ->
315 putMVar mvar value >>
318 -- |Return the contents of the 'MVar'. If the 'MVar' is currently
319 -- empty, 'takeMVar' will wait until it is full. After a 'takeMVar',
320 -- the 'MVar' is left empty.
322 -- If several threads are competing to take the same 'MVar', one is chosen
323 -- to continue at random when the 'MVar' becomes full.
324 takeMVar :: MVar a -> IO a
325 takeMVar (MVar mvar#) = IO $ \ s# -> takeMVar# mvar# s#
327 -- |Put a value into an 'MVar'. If the 'MVar' is currently full,
328 -- 'putMVar' will wait until it becomes empty.
330 -- If several threads are competing to fill the same 'MVar', one is
331 -- chosen to continue at random when the 'MVar' becomes empty.
332 putMVar :: MVar a -> a -> IO ()
333 putMVar (MVar mvar#) x = IO $ \ s# ->
334 case putMVar# mvar# x s# of
337 -- |A non-blocking version of 'takeMVar'. The 'tryTakeMVar' function
338 -- returns immediately, with 'Nothing' if the 'MVar' was empty, or
339 -- @'Just' a@ if the 'MVar' was full with contents @a@. After 'tryTakeMVar',
340 -- the 'MVar' is left empty.
341 tryTakeMVar :: MVar a -> IO (Maybe a)
342 tryTakeMVar (MVar m) = IO $ \ s ->
343 case tryTakeMVar# m s of
344 (# s, 0#, _ #) -> (# s, Nothing #) -- MVar is empty
345 (# s, _, a #) -> (# s, Just a #) -- MVar is full
347 -- |A non-blocking version of 'putMVar'. The 'tryPutMVar' function
348 -- attempts to put the value @a@ into the 'MVar', returning 'True' if
349 -- it was successful, or 'False' otherwise.
350 tryPutMVar :: MVar a -> a -> IO Bool
351 tryPutMVar (MVar mvar#) x = IO $ \ s# ->
352 case tryPutMVar# mvar# x s# of
353 (# s, 0# #) -> (# s, False #)
354 (# s, _ #) -> (# s, True #)
356 -- |Check whether a given 'MVar' is empty.
358 -- Notice that the boolean value returned is just a snapshot of
359 -- the state of the MVar. By the time you get to react on its result,
360 -- the MVar may have been filled (or emptied) - so be extremely
361 -- careful when using this operation. Use 'tryTakeMVar' instead if possible.
362 isEmptyMVar :: MVar a -> IO Bool
363 isEmptyMVar (MVar mv#) = IO $ \ s# ->
364 case isEmptyMVar# mv# s# of
365 (# s2#, flg #) -> (# s2#, not (flg ==# 0#) #)
367 -- |Add a finalizer to an 'MVar' (GHC only). See "Foreign.ForeignPtr" and
368 -- "System.Mem.Weak" for more about finalizers.
369 addMVarFinalizer :: MVar a -> IO () -> IO ()
370 addMVarFinalizer (MVar m) finalizer =
371 IO $ \s -> case mkWeak# m () finalizer s of { (# s1, w #) -> (# s1, () #) }
375 %************************************************************************
377 \subsection{Thread waiting}
379 %************************************************************************
382 #ifdef mingw32_HOST_OS
384 -- Note: threadDelay, threadWaitRead and threadWaitWrite aren't really functional
385 -- on Win32, but left in there because lib code (still) uses them (the manner
386 -- in which they're used doesn't cause problems on a Win32 platform though.)
388 asyncRead :: Int -> Int -> Int -> Ptr a -> IO (Int, Int)
389 asyncRead (I# fd) (I# isSock) (I# len) (Ptr buf) =
390 IO $ \s -> case asyncRead# fd isSock len buf s of
391 (# s, len#, err# #) -> (# s, (I# len#, I# err#) #)
393 asyncWrite :: Int -> Int -> Int -> Ptr a -> IO (Int, Int)
394 asyncWrite (I# fd) (I# isSock) (I# len) (Ptr buf) =
395 IO $ \s -> case asyncWrite# fd isSock len buf s of
396 (# s, len#, err# #) -> (# s, (I# len#, I# err#) #)
398 asyncDoProc :: FunPtr (Ptr a -> IO Int) -> Ptr a -> IO Int
399 asyncDoProc (FunPtr proc) (Ptr param) =
400 -- the 'length' value is ignored; simplifies implementation of
401 -- the async*# primops to have them all return the same result.
402 IO $ \s -> case asyncDoProc# proc param s of
403 (# s, len#, err# #) -> (# s, I# err# #)
405 -- to aid the use of these primops by the IO Handle implementation,
406 -- provide the following convenience funs:
408 -- this better be a pinned byte array!
409 asyncReadBA :: Int -> Int -> Int -> Int -> MutableByteArray# RealWorld -> IO (Int,Int)
410 asyncReadBA fd isSock len off bufB =
411 asyncRead fd isSock len ((Ptr (byteArrayContents# (unsafeCoerce# bufB))) `plusPtr` off)
413 asyncWriteBA :: Int -> Int -> Int -> Int -> MutableByteArray# RealWorld -> IO (Int,Int)
414 asyncWriteBA fd isSock len off bufB =
415 asyncWrite fd isSock len ((Ptr (byteArrayContents# (unsafeCoerce# bufB))) `plusPtr` off)
419 -- -----------------------------------------------------------------------------
422 -- | Block the current thread until data is available to read on the
423 -- given file descriptor (GHC only).
424 threadWaitRead :: Fd -> IO ()
426 #ifndef mingw32_HOST_OS
427 | threaded = waitForReadEvent fd
429 | otherwise = IO $ \s ->
430 case fromIntegral fd of { I# fd# ->
431 case waitRead# fd# s of { s -> (# s, () #)
434 -- | Block the current thread until data can be written to the
435 -- given file descriptor (GHC only).
436 threadWaitWrite :: Fd -> IO ()
438 #ifndef mingw32_HOST_OS
439 | threaded = waitForWriteEvent fd
441 | otherwise = IO $ \s ->
442 case fromIntegral fd of { I# fd# ->
443 case waitWrite# fd# s of { s -> (# s, () #)
446 -- | Suspends the current thread for a given number of microseconds
449 -- Note that the resolution used by the Haskell runtime system's
450 -- internal timer is 1\/50 second, and 'threadDelay' will round its
451 -- argument up to the nearest multiple of this resolution.
453 -- There is no guarantee that the thread will be rescheduled promptly
454 -- when the delay has expired, but the thread will never continue to
455 -- run /earlier/ than specified.
457 threadDelay :: Int -> IO ()
459 #ifndef mingw32_HOST_OS
460 | threaded = waitForDelayEvent time
462 | threaded = c_Sleep (fromIntegral (time `quot` 1000))
464 | otherwise = IO $ \s ->
465 case fromIntegral time of { I# time# ->
466 case delay# time# s of { s -> (# s, () #)
469 -- On Windows, we just make a safe call to 'Sleep' to implement threadDelay.
470 #ifdef mingw32_HOST_OS
471 foreign import ccall safe "Sleep" c_Sleep :: CInt -> IO ()
474 foreign import ccall unsafe "rtsSupportsBoundThreads" threaded :: Bool
476 -- ----------------------------------------------------------------------------
477 -- Threaded RTS implementation of threadWaitRead, threadWaitWrite, threadDelay
479 -- In the threaded RTS, we employ a single IO Manager thread to wait
480 -- for all outstanding IO requests (threadWaitRead,threadWaitWrite)
481 -- and delays (threadDelay).
483 -- We can do this because in the threaded RTS the IO Manager can make
484 -- a non-blocking call to select(), so we don't have to do select() in
485 -- the scheduler as we have to in the non-threaded RTS. We get performance
486 -- benefits from doing it this way, because we only have to restart the select()
487 -- when a new request arrives, rather than doing one select() each time
488 -- around the scheduler loop. Furthermore, the scheduler can be simplified
489 -- by not having to check for completed IO requests.
491 -- Issues, possible problems:
493 -- - we might want bound threads to just do the blocking
494 -- operation rather than communicating with the IO manager
495 -- thread. This would prevent simgle-threaded programs which do
496 -- IO from requiring multiple OS threads. However, it would also
497 -- prevent bound threads waiting on IO from being killed or sent
500 -- - Apprently exec() doesn't work on Linux in a multithreaded program.
501 -- I couldn't repeat this.
503 -- - How do we handle signal delivery in the multithreaded RTS?
505 -- - forkProcess will kill the IO manager thread. Let's just
506 -- hope we don't need to do any blocking IO between fork & exec.
508 #ifndef mingw32_HOST_OS
511 = Read {-# UNPACK #-} !Fd {-# UNPACK #-} !(MVar ())
512 | Write {-# UNPACK #-} !Fd {-# UNPACK #-} !(MVar ())
515 = Delay {-# UNPACK #-} !Int {-# UNPACK #-} !(MVar ())
517 pendingEvents :: IORef [IOReq]
518 pendingDelays :: IORef [DelayReq]
519 -- could use a strict list or array here
520 {-# NOINLINE pendingEvents #-}
521 {-# NOINLINE pendingDelays #-}
522 (pendingEvents,pendingDelays) = unsafePerformIO $ do
527 -- the first time we schedule an IO request, the service thread
528 -- will be created (cool, huh?)
530 startIOServiceThread :: IO ()
531 startIOServiceThread = do
532 allocaArray 2 $ \fds -> do
533 throwErrnoIfMinus1 "startIOServiceThread" (c_pipe fds)
534 rd_end <- peekElemOff fds 0
535 wr_end <- peekElemOff fds 1
536 writeIORef stick (fromIntegral wr_end)
538 allocaBytes sizeofFdSet $ \readfds -> do
539 allocaBytes sizeofFdSet $ \writefds -> do
540 allocaBytes sizeofTimeVal $ \timeval -> do
541 service_loop (fromIntegral rd_end) readfds writefds timeval [] []
544 -- XXX: move real forkIO here from Control.Concurrent?
545 quickForkIO action = IO $ \s ->
546 case (fork# action s) of (# s1, id #) -> (# s1, ThreadId id #)
549 :: Fd -- listen to this for wakeup calls
556 service_loop wakeup readfds writefds ptimeval old_reqs old_delays = do
558 -- pick up new IO requests
559 new_reqs <- atomicModifyIORef pendingEvents (\a -> ([],a))
560 let reqs = new_reqs ++ old_reqs
562 -- pick up new delay requests
563 new_delays <- atomicModifyIORef pendingDelays (\a -> ([],a))
564 let delays = foldr insertDelay old_delays new_delays
566 -- build the FDSets for select()
570 maxfd <- buildFdSets 0 readfds writefds reqs
572 -- check the current time and wake up any thread in threadDelay whose
573 -- timeout has expired. Also find the timeout value for the select() call.
575 (delays', timeout) <- getDelay now ptimeval delays
577 -- perform the select()
579 res <- c_select ((max wakeup maxfd)+1) readfds writefds
590 -- ToDo: check result
592 b <- takeMVar prodding
593 if b then alloca $ \p -> do c_read (fromIntegral wakeup) p 1; return ()
595 putMVar prodding False
597 reqs' <- completeRequests reqs readfds writefds []
598 service_loop wakeup readfds writefds ptimeval reqs' delays'
601 {-# NOINLINE stick #-}
602 stick = unsafePerformIO (newIORef 0)
604 prodding :: MVar Bool
605 {-# NOINLINE prodding #-}
606 prodding = unsafePerformIO (newMVar False)
608 prodServiceThread :: IO ()
609 prodServiceThread = do
610 b <- takeMVar prodding
612 then do fd <- readIORef stick
613 with 42 $ \pbuf -> do c_write (fromIntegral fd) pbuf 1; return ()
615 putMVar prodding True
617 -- -----------------------------------------------------------------------------
620 buildFdSets maxfd readfds writefds [] = return maxfd
621 buildFdSets maxfd readfds writefds (Read fd m : reqs) = do
623 buildFdSets (max maxfd fd) readfds writefds reqs
624 buildFdSets maxfd readfds writefds (Write fd m : reqs) = do
626 buildFdSets (max maxfd fd) readfds writefds reqs
628 completeRequests [] _ _ reqs' = return reqs'
629 completeRequests (Read fd m : reqs) readfds writefds reqs' = do
630 b <- fdIsSet fd readfds
632 then do putMVar m (); completeRequests reqs readfds writefds reqs'
633 else completeRequests reqs readfds writefds (Read fd m : reqs')
634 completeRequests (Write fd m : reqs) readfds writefds reqs' = do
635 b <- fdIsSet fd writefds
637 then do putMVar m (); completeRequests reqs readfds writefds reqs'
638 else completeRequests reqs readfds writefds (Write fd m : reqs')
640 waitForReadEvent :: Fd -> IO ()
641 waitForReadEvent fd = do
643 atomicModifyIORef pendingEvents (\xs -> (Read fd m : xs, ()))
647 waitForWriteEvent :: Fd -> IO ()
648 waitForWriteEvent fd = do
650 atomicModifyIORef pendingEvents (\xs -> (Write fd m : xs, ()))
654 -- XXX: move into GHC.IOBase from Data.IORef?
655 atomicModifyIORef :: IORef a -> (a -> (a,b)) -> IO b
656 atomicModifyIORef (IORef (STRef r#)) f = IO $ \s -> atomicModifyMutVar# r# f s
658 -- -----------------------------------------------------------------------------
661 waitForDelayEvent :: Int -> IO ()
662 waitForDelayEvent usecs = do
665 let target = now + usecs `quot` tick_usecs
666 atomicModifyIORef pendingDelays (\xs -> (Delay target m : xs, ()))
670 -- Walk the queue of pending delays, waking up any that have passed
671 -- and return the smallest delay to wait for. The queue of pending
672 -- delays is kept ordered.
673 getDelay :: Ticks -> Ptr CTimeVal -> [DelayReq] -> IO ([DelayReq], Ptr CTimeVal)
674 getDelay now ptimeval [] = return ([],nullPtr)
675 getDelay now ptimeval all@(Delay time m : rest)
678 getDelay now ptimeval rest
680 setTimevalTicks ptimeval (time - now)
681 return (all,ptimeval)
683 insertDelay :: DelayReq -> [DelayReq] -> [DelayReq]
684 insertDelay d@(Delay time m) [] = [d]
685 insertDelay d1@(Delay time m) ds@(d2@(Delay time' m') : rest)
686 | time <= time' = d1 : ds
687 | otherwise = d2 : insertDelay d1 rest
690 tick_freq = 50 :: Ticks -- accuracy of threadDelay (ticks per sec)
691 tick_usecs = 1000000 `quot` tick_freq :: Int
693 newtype CTimeVal = CTimeVal ()
695 foreign import ccall unsafe "sizeofTimeVal"
698 foreign import ccall unsafe "getTicksOfDay"
699 getTicksOfDay :: IO Ticks
701 foreign import ccall unsafe "setTimevalTicks"
702 setTimevalTicks :: Ptr CTimeVal -> Ticks -> IO ()
704 -- ----------------------------------------------------------------------------
705 -- select() interface
707 -- ToDo: move to System.Posix.Internals?
709 newtype CFdSet = CFdSet ()
711 foreign import ccall safe "select"
712 c_select :: Fd -> Ptr CFdSet -> Ptr CFdSet -> Ptr CFdSet -> Ptr CTimeVal
715 foreign import ccall unsafe "hsFD_CLR"
716 fdClr :: Fd -> Ptr CFdSet -> IO ()
718 foreign import ccall unsafe "hsFD_ISSET"
719 fdIsSet :: Fd -> Ptr CFdSet -> IO CInt
721 foreign import ccall unsafe "hsFD_SET"
722 fdSet :: Fd -> Ptr CFdSet -> IO ()
724 foreign import ccall unsafe "hsFD_ZERO"
725 fdZero :: Ptr CFdSet -> IO ()
727 foreign import ccall unsafe "sizeof_fd_set"