\begin{code}
-{-# OPTIONS -fno-implicit-prelude #-}
+{-# OPTIONS_GHC -XNoImplicitPrelude #-}
+{-# OPTIONS_GHC -fno-warn-missing-signatures #-}
+{-# OPTIONS_HADDOCK not-home #-}
-----------------------------------------------------------------------------
-- |
-- Module : GHC.Conc
--
-----------------------------------------------------------------------------
-#include "config.h"
+-- No: #hide, because bits of this module are exposed by the stm package.
+-- However, we don't want this module to be the home location for the
+-- bits it exports, we'd rather have Control.Concurrent and the other
+-- higher level modules be the home. Hence:
+
+#include "Typeable.h"
+
+-- #not-home
module GHC.Conc
- ( ThreadId(..)
-
- -- Forking and suchlike
- , myThreadId -- :: IO ThreadId
- , killThread -- :: ThreadId -> IO ()
- , throwTo -- :: ThreadId -> Exception -> IO ()
- , par -- :: a -> b -> b
- , pseq -- :: a -> b -> b
- , yield -- :: IO ()
- , labelThread -- :: ThreadId -> String -> IO ()
- , forkProcessPrim -- :: IO Int
- , forkProcess -- :: IO (Maybe Int)
-
- -- Waiting
- , threadDelay -- :: Int -> IO ()
- , threadWaitRead -- :: Int -> IO ()
- , threadWaitWrite -- :: Int -> IO ()
-
- -- MVars
- , MVar -- abstract
- , newMVar -- :: a -> IO (MVar a)
- , newEmptyMVar -- :: IO (MVar a)
- , takeMVar -- :: MVar a -> IO a
- , putMVar -- :: MVar a -> a -> IO ()
- , tryTakeMVar -- :: MVar a -> IO (Maybe a)
- , tryPutMVar -- :: MVar a -> a -> IO Bool
- , isEmptyMVar -- :: MVar a -> IO Bool
- , addMVarFinalizer -- :: MVar a -> IO () -> IO ()
-
-#ifdef mingw32_TARGET_OS
- , asyncRead -- :: Int -> Int -> Int -> Ptr a -> IO (Int, Int)
- , asyncWrite -- :: Int -> Int -> Int -> Ptr a -> IO (Int, Int)
-
- , asyncReadBA -- :: Int -> Int -> Int -> Int -> MutableByteArray# RealWorld -> IO (Int, Int)
- , asyncWriteBA -- :: Int -> Int -> Int -> Int -> MutableByteArray# RealWorld -> IO (Int, Int)
+ ( ThreadId(..)
+
+ -- * Forking and suchlike
+ , forkIO -- :: IO a -> IO ThreadId
+ , forkOnIO -- :: Int -> IO a -> IO ThreadId
+ , numCapabilities -- :: Int
+ , childHandler -- :: Exception -> IO ()
+ , myThreadId -- :: IO ThreadId
+ , killThread -- :: ThreadId -> IO ()
+ , throwTo -- :: ThreadId -> Exception -> IO ()
+ , par -- :: a -> b -> b
+ , pseq -- :: a -> b -> b
+ , runSparks
+ , yield -- :: IO ()
+ , labelThread -- :: ThreadId -> String -> IO ()
+
+ , ThreadStatus(..), BlockReason(..)
+ , threadStatus -- :: ThreadId -> IO ThreadStatus
+
+ -- * Waiting
+ , threadDelay -- :: Int -> IO ()
+ , registerDelay -- :: Int -> IO (TVar Bool)
+ , threadWaitRead -- :: Int -> IO ()
+ , threadWaitWrite -- :: Int -> IO ()
+
+ -- * MVars
+ , MVar(..)
+ , newMVar -- :: a -> IO (MVar a)
+ , newEmptyMVar -- :: IO (MVar a)
+ , takeMVar -- :: MVar a -> IO a
+ , putMVar -- :: MVar a -> a -> IO ()
+ , tryTakeMVar -- :: MVar a -> IO (Maybe a)
+ , tryPutMVar -- :: MVar a -> a -> IO Bool
+ , isEmptyMVar -- :: MVar a -> IO Bool
+ , addMVarFinalizer -- :: MVar a -> IO () -> IO ()
+
+ -- * TVars
+ , STM(..)
+ , atomically -- :: STM a -> IO a
+ , retry -- :: STM a
+ , orElse -- :: STM a -> STM a -> STM a
+ , catchSTM -- :: STM a -> (Exception -> STM a) -> STM a
+ , alwaysSucceeds -- :: STM a -> STM ()
+ , always -- :: STM Bool -> STM ()
+ , TVar(..)
+ , newTVar -- :: a -> STM (TVar a)
+ , newTVarIO -- :: a -> STM (TVar a)
+ , readTVar -- :: TVar a -> STM a
+ , readTVarIO -- :: TVar a -> IO a
+ , writeTVar -- :: a -> TVar a -> STM ()
+ , unsafeIOToSTM -- :: IO a -> STM a
+
+ -- * Miscellaneous
+#ifdef mingw32_HOST_OS
+ , asyncRead -- :: Int -> Int -> Int -> Ptr a -> IO (Int, Int)
+ , asyncWrite -- :: Int -> Int -> Int -> Ptr a -> IO (Int, Int)
+ , asyncDoProc -- :: FunPtr (Ptr a -> IO Int) -> Ptr a -> IO Int
+
+ , asyncReadBA -- :: Int -> Int -> Int -> Int -> MutableByteArray# RealWorld -> IO (Int, Int)
+ , asyncWriteBA -- :: Int -> Int -> Int -> Int -> MutableByteArray# RealWorld -> IO (Int, Int)
+#endif
+
+#ifndef mingw32_HOST_OS
+ , Signal, HandlerFun, setHandler, runHandlers
#endif
+
+ , ensureIOManagerIsRunning
+ , syncIOManager
+
+#ifdef mingw32_HOST_OS
+ , ConsoleEvent(..)
+ , win32ConsoleHandler
+ , toWin32ConsoleEvent
+#endif
+ , setUncaughtExceptionHandler -- :: (Exception -> IO ()) -> IO ()
+ , getUncaughtExceptionHandler -- :: IO (Exception -> IO ())
+
+ , reportError, reportStackOverflow
) where
+import System.Posix.Types
+#ifndef mingw32_HOST_OS
+import System.Posix.Internals
+#endif
+import Foreign
+import Foreign.C
+
+import Data.Dynamic
import Data.Maybe
+import Control.Monad
import GHC.Base
-import GHC.IOBase ( IO(..), MVar(..), ioException, IOException(..), IOErrorType(..) )
-import GHC.Num ( fromInteger, negate )
-import GHC.Base ( Int(..) )
-import GHC.Exception ( Exception(..), AsyncException(..) )
-import GHC.Pack ( packCString# )
-import GHC.Ptr ( Ptr(..), plusPtr )
+import {-# SOURCE #-} GHC.Handle
+import GHC.IOBase
+import GHC.Num ( Num(..) )
+import GHC.Real ( fromIntegral )
+import GHC.Arr ( inRange )
+#ifdef mingw32_HOST_OS
+import GHC.Real ( div )
+import GHC.Ptr ( plusPtr, FunPtr(..) )
+#endif
+#ifdef mingw32_HOST_OS
+import GHC.Read ( Read )
+import GHC.Enum ( Enum )
+#endif
+import GHC.Exception ( SomeException(..), throw )
+import GHC.Pack ( packCString# )
+import GHC.Ptr ( Ptr(..) )
+import GHC.STRef
+import GHC.Show ( Show(..), showString )
+import Data.Typeable
+import GHC.Err
infixr 0 `par`, `pseq`
\end{code}
%************************************************************************
-%* *
+%* *
\subsection{@ThreadId@, @par@, and @fork@}
-%* *
+%* *
%************************************************************************
\begin{code}
-data ThreadId = ThreadId ThreadId#
+data ThreadId = ThreadId ThreadId# deriving( Typeable )
-- ToDo: data ThreadId = ThreadId (Weak ThreadId#)
-- But since ThreadId# is unlifted, the Weak type must use open
-- type variables.
useful when debugging or diagnosing the behaviour of a concurrent
program.
-NOTE: in GHC, if you have a 'ThreadId', you essentially have
+/Note/: in GHC, if you have a 'ThreadId', you essentially have
a pointer to the thread itself. This means the thread itself can\'t be
garbage collected until you drop the 'ThreadId'.
This misfeature will hopefully be corrected at a later date.
+
+/Note/: Hugs does not provide any operations on other threads;
+it defines 'ThreadId' as a synonym for ().
+-}
+
+instance Show ThreadId where
+ showsPrec d t =
+ showString "ThreadId " .
+ showsPrec d (getThreadId (id2TSO t))
+
+foreign import ccall unsafe "rts_getThreadId" getThreadId :: ThreadId# -> CInt
+
+id2TSO :: ThreadId -> ThreadId#
+id2TSO (ThreadId t) = t
+
+foreign import ccall unsafe "cmp_thread" cmp_thread :: ThreadId# -> ThreadId# -> CInt
+-- Returns -1, 0, 1
+
+cmpThread :: ThreadId -> ThreadId -> Ordering
+cmpThread t1 t2 =
+ case cmp_thread (id2TSO t1) (id2TSO 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
+
+{- |
+Sparks off a new thread to run the 'IO' computation passed as the
+first argument, and returns the 'ThreadId' of the newly created
+thread.
+
+The new thread will be a lightweight thread; if you want to use a foreign
+library that uses thread-local storage, use 'Control.Concurrent.forkOS' instead.
+
+GHC note: the new thread inherits the /blocked/ state of the parent
+(see 'Control.Exception.block').
+
+The newly created thread has an exception handler that discards the
+exceptions 'BlockedOnDeadMVar', 'BlockedIndefinitely', and
+'ThreadKilled', and passes all other exceptions to the uncaught
+exception handler (see 'setUncaughtExceptionHandler').
+-}
+forkIO :: IO () -> IO ThreadId
+forkIO action = IO $ \ s ->
+ case (fork# action_plus s) of (# s1, tid #) -> (# s1, ThreadId tid #)
+ where
+ action_plus = catchException action childHandler
+
+{- |
+Like 'forkIO', but lets you specify on which CPU the thread is
+created. Unlike a `forkIO` thread, a thread created by `forkOnIO`
+will stay on the same CPU for its entire lifetime (`forkIO` threads
+can migrate between CPUs according to the scheduling policy).
+`forkOnIO` is useful for overriding the scheduling policy when you
+know in advance how best to distribute the threads.
+
+The `Int` argument specifies the CPU number; it is interpreted modulo
+'numCapabilities' (note that it actually specifies a capability number
+rather than a CPU number, but to a first approximation the two are
+equivalent).
-}
+forkOnIO :: Int -> IO () -> IO ThreadId
+forkOnIO (I# cpu) action = IO $ \ s ->
+ case (forkOn# cpu action_plus s) of (# s1, tid #) -> (# s1, ThreadId tid #)
+ where
+ action_plus = catchException action childHandler
+
+-- | the value passed to the @+RTS -N@ flag. This is the number of
+-- Haskell threads that can run truly simultaneously at any given
+-- time, and is typically set to the number of physical CPU cores on
+-- the machine.
+numCapabilities :: Int
+numCapabilities = unsafePerformIO $ do
+ n <- peek n_capabilities
+ return (fromIntegral n)
+
+#if defined(mingw32_HOST_OS) && defined(__PIC__)
+foreign import ccall "_imp__n_capabilities" n_capabilities :: Ptr CInt
+#else
+foreign import ccall "&n_capabilities" n_capabilities :: Ptr CInt
+#endif
+childHandler :: SomeException -> IO ()
+childHandler err = catchException (real_handler err) childHandler
---forkIO has now been hoisted out into the Concurrent library.
+real_handler :: SomeException -> IO ()
+real_handler se@(SomeException ex) =
+ -- ignore thread GC and killThread exceptions:
+ case cast ex of
+ Just BlockedOnDeadMVar -> return ()
+ _ -> case cast ex of
+ Just BlockedIndefinitely -> return ()
+ _ -> case cast ex of
+ Just ThreadKilled -> return ()
+ _ -> case cast ex of
+ -- report all others:
+ Just StackOverflow -> reportStackOverflow
+ _ -> reportError se
-{- | 'killThread' terminates the given thread (Note: 'killThread' is
-not implemented in Hugs). Any work already done by the thread isn\'t
+{- | 'killThread' terminates the given thread (GHC only).
+Any work already done by the thread isn\'t
lost: the computation is suspended until required by another thread.
The memory used by the thread will be garbage collected if it isn\'t
referenced from anywhere. The 'killThread' function is defined in
terms of 'throwTo':
-> killThread tid = throwTo tid (AsyncException ThreadKilled)
+> killThread tid = throwTo tid ThreadKilled
+Killthread is a no-op if the target thread has already completed.
-}
killThread :: ThreadId -> IO ()
-killThread tid = throwTo tid (AsyncException ThreadKilled)
+killThread tid = throwTo tid ThreadKilled
-{- | 'throwTo' raises an arbitrary exception in the target thread.
+{- | 'throwTo' raises an arbitrary exception in the target thread (GHC only).
'throwTo' does not return until the exception has been raised in the
-target thread. The calling thread can thus be certain that the target
+target thread.
+The calling thread can thus be certain that the target
thread has received the exception. This is a useful property to know
when dealing with race conditions: eg. if there are two threads that
can kill each other, it is guaranteed that only one of the threads
-will get to kill the other. -}
-throwTo :: ThreadId -> Exception -> IO ()
-throwTo (ThreadId id) ex = IO $ \ s ->
- case (killThread# id ex s) of s1 -> (# s1, () #)
+will get to kill the other.
--- | Returns the 'ThreadId' of the calling thread.
+If the target thread is currently making a foreign call, then the
+exception will not be raised (and hence 'throwTo' will not return)
+until the call has completed. This is the case regardless of whether
+the call is inside a 'block' or not.
+
+Important note: the behaviour of 'throwTo' differs from that described in
+the paper \"Asynchronous exceptions in Haskell\"
+(<http://research.microsoft.com/~simonpj/Papers/asynch-exns.htm>).
+In the paper, 'throwTo' is non-blocking; but the library implementation adopts
+a more synchronous design in which 'throwTo' does not return until the exception
+is received by the target thread. The trade-off is discussed in Section 9 of the paper.
+Like any blocking operation, 'throwTo' is therefore interruptible (see Section 5.3 of
+the paper).
+
+There is currently no guarantee that the exception delivered by 'throwTo' will be
+delivered at the first possible opportunity. In particular, a thread may
+unblock and then re-block exceptions (using 'unblock' and 'block') without receiving
+a pending 'throwTo'. This is arguably undesirable behaviour.
+
+ -}
+throwTo :: Exception e => ThreadId -> e -> IO ()
+throwTo (ThreadId tid) ex = IO $ \ s ->
+ case (killThread# tid (toException ex) s) of s1 -> (# s1, () #)
+
+-- | Returns the 'ThreadId' of the calling thread (GHC only).
myThreadId :: IO ThreadId
myThreadId = IO $ \s ->
- case (myThreadId# s) of (# s1, id #) -> (# s1, ThreadId id #)
+ case (myThreadId# s) of (# s1, tid #) -> (# s1, ThreadId tid #)
-- |The 'yield' action allows (forces, in a co-operative multitasking
adr = byteArrayContents# ps in
case (labelThread# t adr s) of s1 -> (# s1, () #)
-{- | This function is a replacement for "Posix.forkProcess": This implementation
-/will stop all other Concurrent Haskell threads/ in the (heavyweight) forked copy.
-'forkProcessPrim' returns the pid of the child process to the parent, 0 to the child,
-and a value less than 0 in case of errors. See also: 'forkProcess'.
-
-Without this function, you need excessive and often impractical
-explicit synchronization using the regular Concurrent Haskell constructs to assure
-that only the desired thread is running after the fork().
-
-The stopped threads are /not/ garbage collected! This behaviour may change in
-future releases.
-
-NOTE: currently, main threads are not stopped in the child process.
-To work around this problem, call 'forkProcessPrim' from the main thread.
--}
-
-forkProcessPrim :: IO Int
-forkProcessPrim = IO $ \s -> case (forkProcess# s) of (# s1, id #) -> (# s1, (I# id) #)
-
-{- | 'forkProcess' is a wrapper around 'forkProcessPrim' similar to the one found in
-"Posix.forkProcess" which returns a Maybe-type. The child receives @Nothing@, the
-parent @Just (pid::Int)@. In case of an error, an exception is thrown.
-
-NOTE: currently, main threads are not stopped in the child process.
-To work around this problem, call 'forkProcess' from the main thread.
--}
-
-forkProcess :: IO (Maybe Int)
-forkProcess = do
- pid <- forkProcessPrim
- case pid of
- -1 -> ioException (IOError Nothing -- stolen from hslibs/posix/PosixUtil
- SystemError
- "forkProcess"
- ""
- Nothing)
- 0 -> return Nothing
- _ -> return (Just pid)
-
--- Nota Bene: 'pseq' used to be 'seq'
--- but 'seq' is now defined in PrelGHC
+-- Nota Bene: 'pseq' used to be 'seq'
+-- but 'seq' is now defined in PrelGHC
--
-- "pseq" is defined a bit weirdly (see below)
--
{-# INLINE par #-}
par :: a -> b -> b
par x y = case (par# x) of { _ -> lazy y }
+
+-- | Internal function used by the RTS to run sparks.
+runSparks :: IO ()
+runSparks = IO loop
+ where loop s = case getSpark# s of
+ (# s', n, p #) ->
+ if n ==# 0# then (# s', () #)
+ else p `seq` loop s'
+
+data BlockReason
+ = BlockedOnMVar
+ -- ^blocked on on 'MVar'
+ | BlockedOnBlackHole
+ -- ^blocked on a computation in progress by another thread
+ | BlockedOnException
+ -- ^blocked in 'throwTo'
+ | BlockedOnSTM
+ -- ^blocked in 'retry' in an STM transaction
+ | BlockedOnForeignCall
+ -- ^currently in a foreign call
+ | BlockedOnOther
+ -- ^blocked on some other resource. Without @-threaded@,
+ -- I\/O and 'threadDelay' show up as 'BlockedOnOther', with @-threaded@
+ -- they show up as 'BlockedOnMVar'.
+ deriving (Eq,Ord,Show)
+
+-- | The current status of a thread
+data ThreadStatus
+ = ThreadRunning
+ -- ^the thread is currently runnable or running
+ | ThreadFinished
+ -- ^the thread has finished
+ | ThreadBlocked BlockReason
+ -- ^the thread is blocked on some resource
+ | ThreadDied
+ -- ^the thread received an uncaught exception
+ deriving (Eq,Ord,Show)
+
+threadStatus :: ThreadId -> IO ThreadStatus
+threadStatus (ThreadId t) = IO $ \s ->
+ case threadStatus# t s of
+ (# s', stat #) -> (# s', mk_stat (I# stat) #)
+ where
+ -- NB. keep these in sync with includes/Constants.h
+ mk_stat 0 = ThreadRunning
+ mk_stat 1 = ThreadBlocked BlockedOnMVar
+ mk_stat 2 = ThreadBlocked BlockedOnBlackHole
+ mk_stat 3 = ThreadBlocked BlockedOnException
+ mk_stat 7 = ThreadBlocked BlockedOnSTM
+ mk_stat 11 = ThreadBlocked BlockedOnForeignCall
+ mk_stat 12 = ThreadBlocked BlockedOnForeignCall
+ mk_stat 16 = ThreadFinished
+ mk_stat 17 = ThreadDied
+ mk_stat _ = ThreadBlocked BlockedOnOther
\end{code}
+
+%************************************************************************
+%* *
+\subsection[stm]{Transactional heap operations}
+%* *
%************************************************************************
-%* *
+
+TVars are shared memory locations which support atomic memory
+transactions.
+
+\begin{code}
+-- |A monad supporting atomic memory transactions.
+newtype STM a = STM (State# RealWorld -> (# State# RealWorld, a #))
+
+unSTM :: STM a -> (State# RealWorld -> (# State# RealWorld, a #))
+unSTM (STM a) = a
+
+INSTANCE_TYPEABLE1(STM,stmTc,"STM")
+
+instance Functor STM where
+ fmap f x = x >>= (return . f)
+
+instance Monad STM where
+ {-# INLINE return #-}
+ {-# INLINE (>>) #-}
+ {-# INLINE (>>=) #-}
+ m >> k = thenSTM m k
+ return x = returnSTM x
+ m >>= k = bindSTM m k
+
+bindSTM :: STM a -> (a -> STM b) -> STM b
+bindSTM (STM m) k = STM ( \s ->
+ case m s of
+ (# new_s, a #) -> unSTM (k a) new_s
+ )
+
+thenSTM :: STM a -> STM b -> STM b
+thenSTM (STM m) k = STM ( \s ->
+ case m s of
+ (# new_s, _ #) -> unSTM k new_s
+ )
+
+returnSTM :: a -> STM a
+returnSTM x = STM (\s -> (# s, x #))
+
+-- | Unsafely performs IO in the STM monad. Beware: this is a highly
+-- dangerous thing to do.
+--
+-- * The STM implementation will often run transactions multiple
+-- times, so you need to be prepared for this if your IO has any
+-- side effects.
+--
+-- * The STM implementation will abort transactions that are known to
+-- be invalid and need to be restarted. This may happen in the middle
+-- of `unsafeIOToSTM`, so make sure you don't acquire any resources
+-- that need releasing (exception handlers are ignored when aborting
+-- the transaction). That includes doing any IO using Handles, for
+-- example. Getting this wrong will probably lead to random deadlocks.
+--
+-- * The transaction may have seen an inconsistent view of memory when
+-- the IO runs. Invariants that you expect to be true throughout
+-- your program may not be true inside a transaction, due to the
+-- way transactions are implemented. Normally this wouldn't be visible
+-- to the programmer, but using `unsafeIOToSTM` can expose it.
+--
+unsafeIOToSTM :: IO a -> STM a
+unsafeIOToSTM (IO m) = STM m
+
+-- |Perform a series of STM actions atomically.
+--
+-- You cannot use 'atomically' inside an 'unsafePerformIO' or 'unsafeInterleaveIO'.
+-- Any attempt to do so will result in a runtime error. (Reason: allowing
+-- this would effectively allow a transaction inside a transaction, depending
+-- on exactly when the thunk is evaluated.)
+--
+-- However, see 'newTVarIO', which can be called inside 'unsafePerformIO',
+-- and which allows top-level TVars to be allocated.
+
+atomically :: STM a -> IO a
+atomically (STM m) = IO (\s -> (atomically# m) s )
+
+-- |Retry execution of the current memory transaction because it has seen
+-- values in TVars which mean that it should not continue (e.g. the TVars
+-- represent a shared buffer that is now empty). The implementation may
+-- block the thread until one of the TVars that it has read from has been
+-- udpated. (GHC only)
+retry :: STM a
+retry = STM $ \s# -> retry# s#
+
+-- |Compose two alternative STM actions (GHC only). If the first action
+-- completes without retrying then it forms the result of the orElse.
+-- Otherwise, if the first action retries, then the second action is
+-- tried in its place. If both actions retry then the orElse as a
+-- whole retries.
+orElse :: STM a -> STM a -> STM a
+orElse (STM m) e = STM $ \s -> catchRetry# m (unSTM e) s
+
+-- |Exception handling within STM actions.
+catchSTM :: STM a -> (SomeException -> STM a) -> STM a
+catchSTM (STM m) k = STM $ \s -> catchSTM# m (\ex -> unSTM (k ex)) s
+
+-- | Low-level primitive on which always and alwaysSucceeds are built.
+-- checkInv differs form these in that (i) the invariant is not
+-- checked when checkInv is called, only at the end of this and
+-- subsequent transcations, (ii) the invariant failure is indicated
+-- by raising an exception.
+checkInv :: STM a -> STM ()
+checkInv (STM m) = STM (\s -> (check# m) s)
+
+-- | alwaysSucceeds adds a new invariant that must be true when passed
+-- to alwaysSucceeds, at the end of the current transaction, and at
+-- the end of every subsequent transaction. If it fails at any
+-- of those points then the transaction violating it is aborted
+-- and the exception raised by the invariant is propagated.
+alwaysSucceeds :: STM a -> STM ()
+alwaysSucceeds i = do ( do i ; retry ) `orElse` ( return () )
+ checkInv i
+
+-- | always is a variant of alwaysSucceeds in which the invariant is
+-- expressed as an STM Bool action that must return True. Returning
+-- False or raising an exception are both treated as invariant failures.
+always :: STM Bool -> STM ()
+always i = alwaysSucceeds ( do v <- i
+ if (v) then return () else ( error "Transacional invariant violation" ) )
+
+-- |Shared memory locations that support atomic memory transactions.
+data TVar a = TVar (TVar# RealWorld a)
+
+INSTANCE_TYPEABLE1(TVar,tvarTc,"TVar")
+
+instance Eq (TVar a) where
+ (TVar tvar1#) == (TVar tvar2#) = sameTVar# tvar1# tvar2#
+
+-- |Create a new TVar holding a value supplied
+newTVar :: a -> STM (TVar a)
+newTVar val = STM $ \s1# ->
+ case newTVar# val s1# of
+ (# s2#, tvar# #) -> (# s2#, TVar tvar# #)
+
+-- |@IO@ version of 'newTVar'. This is useful for creating top-level
+-- 'TVar's using 'System.IO.Unsafe.unsafePerformIO', because using
+-- 'atomically' inside 'System.IO.Unsafe.unsafePerformIO' isn't
+-- possible.
+newTVarIO :: a -> IO (TVar a)
+newTVarIO val = IO $ \s1# ->
+ case newTVar# val s1# of
+ (# s2#, tvar# #) -> (# s2#, TVar tvar# #)
+
+-- |Return the current value stored in a TVar.
+-- This is equivalent to
+--
+-- > readTVarIO = atomically . readTVar
+--
+-- but works much faster, because it doesn't perform a complete
+-- transaction, it just reads the current value of the 'TVar'.
+readTVarIO :: TVar a -> IO a
+readTVarIO (TVar tvar#) = IO $ \s# -> readTVarIO# tvar# s#
+
+-- |Return the current value stored in a TVar
+readTVar :: TVar a -> STM a
+readTVar (TVar tvar#) = STM $ \s# -> readTVar# tvar# s#
+
+-- |Write the supplied value into a TVar
+writeTVar :: TVar a -> a -> STM ()
+writeTVar (TVar tvar#) val = STM $ \s1# ->
+ case writeTVar# tvar# val s1# of
+ s2# -> (# s2#, () #)
+
+\end{code}
+
+%************************************************************************
+%* *
\subsection[mvars]{M-Structures}
-%* *
+%* *
%************************************************************************
M-Vars are rendezvous points for concurrent threads. They begin
-- |Create an 'MVar' which contains the supplied value.
newMVar :: a -> IO (MVar a)
newMVar value =
- newEmptyMVar >>= \ mvar ->
- putMVar mvar value >>
+ newEmptyMVar >>= \ mvar ->
+ putMVar mvar value >>
return mvar
-- |Return the contents of the 'MVar'. If the 'MVar' is currently
-- empty, 'takeMVar' will wait until it is full. After a 'takeMVar',
-- the 'MVar' is left empty.
--
--- If several threads are competing to take the same 'MVar', one is chosen
--- to continue at random when the 'MVar' becomes full.
+-- There are two further important properties of 'takeMVar':
+--
+-- * 'takeMVar' is single-wakeup. That is, if there are multiple
+-- threads blocked in 'takeMVar', and the 'MVar' becomes full,
+-- only one thread will be woken up. The runtime guarantees that
+-- the woken thread completes its 'takeMVar' operation.
+--
+-- * When multiple threads are blocked on an 'MVar', they are
+-- woken up in FIFO order. This is useful for providing
+-- fairness properties of abstractions built using 'MVar's.
+--
takeMVar :: MVar a -> IO a
takeMVar (MVar mvar#) = IO $ \ s# -> takeMVar# mvar# s#
-- |Put a value into an 'MVar'. If the 'MVar' is currently full,
-- 'putMVar' will wait until it becomes empty.
--
--- If several threads are competing to fill the same 'MVar', one is
--- chosen to continue at random with the 'MVar' becomes empty.
+-- There are two further important properties of 'putMVar':
+--
+-- * 'putMVar' is single-wakeup. That is, if there are multiple
+-- threads blocked in 'putMVar', and the 'MVar' becomes empty,
+-- only one thread will be woken up. The runtime guarantees that
+-- the woken thread completes its 'putMVar' operation.
+--
+-- * When multiple threads are blocked on an 'MVar', they are
+-- woken up in FIFO order. This is useful for providing
+-- fairness properties of abstractions built using 'MVar's.
+--
putMVar :: MVar a -> a -> IO ()
putMVar (MVar mvar#) x = IO $ \ s# ->
case putMVar# mvar# x s# of
tryTakeMVar :: MVar a -> IO (Maybe a)
tryTakeMVar (MVar m) = IO $ \ s ->
case tryTakeMVar# m s of
- (# s, 0#, _ #) -> (# s, Nothing #) -- MVar is empty
- (# s, _, a #) -> (# s, Just a #) -- MVar is full
+ (# s', 0#, _ #) -> (# s', Nothing #) -- MVar is empty
+ (# s', _, a #) -> (# s', Just a #) -- MVar is full
-- |A non-blocking version of 'putMVar'. The 'tryPutMVar' function
-- attempts to put the value @a@ into the 'MVar', returning 'True' if
case isEmptyMVar# mv# s# of
(# s2#, flg #) -> (# s2#, not (flg ==# 0#) #)
--- |Add a finalizer to an 'MVar'. See "Foreign.ForeignPtr" and
+-- |Add a finalizer to an 'MVar' (GHC only). See "Foreign.ForeignPtr" and
-- "System.Mem.Weak" for more about finalizers.
addMVarFinalizer :: MVar a -> IO () -> IO ()
addMVarFinalizer (MVar m) finalizer =
- IO $ \s -> case mkWeak# m () finalizer s of { (# s1, w #) -> (# s1, () #) }
+ IO $ \s -> case mkWeak# m () finalizer s of { (# s1, _ #) -> (# s1, () #) }
\end{code}
%************************************************************************
-%* *
+%* *
\subsection{Thread waiting}
-%* *
+%* *
%************************************************************************
-@threadWaitRead@ delays rescheduling of a thread until input on the
-specified file descriptor is available for reading (just like select).
-@threadWaitWrite@ is similar, but for writing on a file descriptor.
-
\begin{code}
--- |The 'threadDelay' operation will cause the current thread to
--- suspend for a given number of microseconds. Note that the resolution
--- used by the Haskell runtime system\'s internal timer together with the
--- fact that the thread may take some time to be rescheduled after the
--- time has expired, means that the accuracy is more like 1\/50 second.
-threadDelay :: Int -> IO ()
+#ifdef mingw32_HOST_OS
--- | Block the current thread until data is available to read on the
--- given file descriptor.
-threadWaitRead :: Int -> IO ()
-
--- | Block the current thread until data can be written to the
--- given file descriptor.
-threadWaitWrite :: Int -> IO ()
-
-threadDelay (I# ms) = IO $ \s -> case delay# ms s of s -> (# s, () #)
-threadWaitRead (I# fd) = IO $ \s -> case waitRead# fd s of s -> (# s, () #)
-threadWaitWrite (I# fd) = IO $ \s -> case waitWrite# fd s of s -> (# s, () #)
-
-#ifdef mingw32_TARGET_OS
-
--- Note: threadDelay, threadWaitRead and threadWaitWrite aren't really functional
+-- Note: threadWaitRead and threadWaitWrite aren't really functional
-- on Win32, but left in there because lib code (still) uses them (the manner
-- in which they're used doesn't cause problems on a Win32 platform though.)
asyncRead :: Int -> Int -> Int -> Ptr a -> IO (Int, Int)
-asyncRead (I# fd) (I# isSock) (I# len) (Ptr buf) =
- IO $ \s -> case asyncRead# fd isSock len buf s of
- (# s, len#, err# #) -> (# s, (I# len#, I# err#) #)
+asyncRead (I# fd) (I# isSock) (I# len) (Ptr buf) =
+ IO $ \s -> case asyncRead# fd isSock len buf s of
+ (# s', len#, err# #) -> (# s', (I# len#, I# err#) #)
asyncWrite :: Int -> Int -> Int -> Ptr a -> IO (Int, Int)
-asyncWrite (I# fd) (I# isSock) (I# len) (Ptr buf) =
- IO $ \s -> case asyncWrite# fd isSock len buf s of
- (# s, len#, err# #) -> (# s, (I# len#, I# err#) #)
+asyncWrite (I# fd) (I# isSock) (I# len) (Ptr buf) =
+ IO $ \s -> case asyncWrite# fd isSock len buf s of
+ (# s', len#, err# #) -> (# s', (I# len#, I# err#) #)
+
+asyncDoProc :: FunPtr (Ptr a -> IO Int) -> Ptr a -> IO Int
+asyncDoProc (FunPtr proc) (Ptr param) =
+ -- the 'length' value is ignored; simplifies implementation of
+ -- the async*# primops to have them all return the same result.
+ IO $ \s -> case asyncDoProc# proc param s of
+ (# s', _len#, err# #) -> (# s', I# err# #)
-- to aid the use of these primops by the IO Handle implementation,
-- provide the following convenience funs:
asyncWrite fd isSock len ((Ptr (byteArrayContents# (unsafeCoerce# bufB))) `plusPtr` off)
#endif
+
+-- -----------------------------------------------------------------------------
+-- Thread IO API
+
+-- | Block the current thread until data is available to read on the
+-- given file descriptor (GHC only).
+threadWaitRead :: Fd -> IO ()
+threadWaitRead fd
+#ifndef mingw32_HOST_OS
+ | threaded = waitForReadEvent fd
+#endif
+ | otherwise = IO $ \s ->
+ case fromIntegral fd of { I# fd# ->
+ case waitRead# fd# s of { s' -> (# s', () #)
+ }}
+
+-- | Block the current thread until data can be written to the
+-- given file descriptor (GHC only).
+threadWaitWrite :: Fd -> IO ()
+threadWaitWrite fd
+#ifndef mingw32_HOST_OS
+ | threaded = waitForWriteEvent fd
+#endif
+ | otherwise = IO $ \s ->
+ case fromIntegral fd of { I# fd# ->
+ case waitWrite# fd# s of { s' -> (# s', () #)
+ }}
+
+-- | Suspends the current thread for a given number of microseconds
+-- (GHC only).
+--
+-- There is no guarantee that the thread will be rescheduled promptly
+-- when the delay has expired, but the thread will never continue to
+-- run /earlier/ than specified.
+--
+threadDelay :: Int -> IO ()
+threadDelay time
+ | threaded = waitForDelayEvent time
+ | otherwise = IO $ \s ->
+ case fromIntegral time of { I# time# ->
+ case delay# time# s of { s' -> (# s', () #)
+ }}
+
+
+-- | Set the value of returned TVar to True after a given number of
+-- microseconds. The caveats associated with threadDelay also apply.
+--
+registerDelay :: Int -> IO (TVar Bool)
+registerDelay usecs
+ | threaded = waitForDelayEventSTM usecs
+ | otherwise = error "registerDelay: requires -threaded"
+
+foreign import ccall unsafe "rtsSupportsBoundThreads" threaded :: Bool
+
+waitForDelayEvent :: Int -> IO ()
+waitForDelayEvent usecs = do
+ m <- newEmptyMVar
+ target <- calculateTarget usecs
+ atomicModifyIORef pendingDelays (\xs -> (Delay target m : xs, ()))
+ prodServiceThread
+ takeMVar m
+
+-- Delays for use in STM
+waitForDelayEventSTM :: Int -> IO (TVar Bool)
+waitForDelayEventSTM usecs = do
+ t <- atomically $ newTVar False
+ target <- calculateTarget usecs
+ atomicModifyIORef pendingDelays (\xs -> (DelaySTM target t : xs, ()))
+ prodServiceThread
+ return t
+
+calculateTarget :: Int -> IO USecs
+calculateTarget usecs = do
+ now <- getUSecOfDay
+ return $ now + (fromIntegral usecs)
+
+
+-- ----------------------------------------------------------------------------
+-- Threaded RTS implementation of threadWaitRead, threadWaitWrite, threadDelay
+
+-- In the threaded RTS, we employ a single IO Manager thread to wait
+-- for all outstanding IO requests (threadWaitRead,threadWaitWrite)
+-- and delays (threadDelay).
+--
+-- We can do this because in the threaded RTS the IO Manager can make
+-- a non-blocking call to select(), so we don't have to do select() in
+-- the scheduler as we have to in the non-threaded RTS. We get performance
+-- benefits from doing it this way, because we only have to restart the select()
+-- when a new request arrives, rather than doing one select() each time
+-- around the scheduler loop. Furthermore, the scheduler can be simplified
+-- by not having to check for completed IO requests.
+
+-- Issues, possible problems:
+--
+-- - we might want bound threads to just do the blocking
+-- operation rather than communicating with the IO manager
+-- thread. This would prevent simgle-threaded programs which do
+-- IO from requiring multiple OS threads. However, it would also
+-- prevent bound threads waiting on IO from being killed or sent
+-- exceptions.
+--
+-- - Apprently exec() doesn't work on Linux in a multithreaded program.
+-- I couldn't repeat this.
+--
+-- - How do we handle signal delivery in the multithreaded RTS?
+--
+-- - forkProcess will kill the IO manager thread. Let's just
+-- hope we don't need to do any blocking IO between fork & exec.
+
+#ifndef mingw32_HOST_OS
+data IOReq
+ = Read {-# UNPACK #-} !Fd {-# UNPACK #-} !(MVar ())
+ | Write {-# UNPACK #-} !Fd {-# UNPACK #-} !(MVar ())
+#endif
+
+data DelayReq
+ = Delay {-# UNPACK #-} !USecs {-# UNPACK #-} !(MVar ())
+ | DelaySTM {-# UNPACK #-} !USecs {-# UNPACK #-} !(TVar Bool)
+
+#ifndef mingw32_HOST_OS
+pendingEvents :: IORef [IOReq]
+#endif
+pendingDelays :: IORef [DelayReq]
+ -- could use a strict list or array here
+{-# NOINLINE pendingEvents #-}
+{-# NOINLINE pendingDelays #-}
+(pendingEvents,pendingDelays) = unsafePerformIO $ do
+ startIOManagerThread
+ reqs <- newIORef []
+ dels <- newIORef []
+ return (reqs, dels)
+ -- the first time we schedule an IO request, the service thread
+ -- will be created (cool, huh?)
+
+ensureIOManagerIsRunning :: IO ()
+ensureIOManagerIsRunning
+ | threaded = seq pendingEvents $ return ()
+ | otherwise = return ()
+
+insertDelay :: DelayReq -> [DelayReq] -> [DelayReq]
+insertDelay d [] = [d]
+insertDelay d1 ds@(d2 : rest)
+ | delayTime d1 <= delayTime d2 = d1 : ds
+ | otherwise = d2 : insertDelay d1 rest
+
+delayTime :: DelayReq -> USecs
+delayTime (Delay t _) = t
+delayTime (DelaySTM t _) = t
+
+type USecs = Word64
+
+-- XXX: move into GHC.IOBase from Data.IORef?
+atomicModifyIORef :: IORef a -> (a -> (a,b)) -> IO b
+atomicModifyIORef (IORef (STRef r#)) f = IO $ \s -> atomicModifyMutVar# r# f s
+
+foreign import ccall unsafe "getUSecOfDay"
+ getUSecOfDay :: IO USecs
+
+prodding :: IORef Bool
+{-# NOINLINE prodding #-}
+prodding = unsafePerformIO (newIORef False)
+
+prodServiceThread :: IO ()
+prodServiceThread = do
+ was_set <- atomicModifyIORef prodding (\a -> (True,a))
+ if (not (was_set)) then wakeupIOManager else return ()
+
+#ifdef mingw32_HOST_OS
+-- ----------------------------------------------------------------------------
+-- Windows IO manager thread
+
+startIOManagerThread :: IO ()
+startIOManagerThread = do
+ wakeup <- c_getIOManagerEvent
+ forkIO $ service_loop wakeup []
+ return ()
+
+service_loop :: HANDLE -- read end of pipe
+ -> [DelayReq] -- current delay requests
+ -> IO ()
+
+service_loop wakeup old_delays = do
+ -- pick up new delay requests
+ new_delays <- atomicModifyIORef pendingDelays (\a -> ([],a))
+ let delays = foldr insertDelay old_delays new_delays
+
+ now <- getUSecOfDay
+ (delays', timeout) <- getDelay now delays
+
+ r <- c_WaitForSingleObject wakeup timeout
+ case r of
+ 0xffffffff -> do c_maperrno; throwErrno "service_loop"
+ 0 -> do
+ r2 <- c_readIOManagerEvent
+ exit <-
+ case r2 of
+ _ | r2 == io_MANAGER_WAKEUP -> return False
+ _ | r2 == io_MANAGER_DIE -> return True
+ 0 -> return False -- spurious wakeup
+ _ -> do start_console_handler (r2 `shiftR` 1); return False
+ if exit
+ then return ()
+ else service_cont wakeup delays'
+
+ _other -> service_cont wakeup delays' -- probably timeout
+
+service_cont :: HANDLE -> [DelayReq] -> IO ()
+service_cont wakeup delays = do
+ atomicModifyIORef prodding (\_ -> (False,False))
+ service_loop wakeup delays
+
+-- must agree with rts/win32/ThrIOManager.c
+io_MANAGER_WAKEUP, io_MANAGER_DIE :: Word32
+io_MANAGER_WAKEUP = 0xffffffff
+io_MANAGER_DIE = 0xfffffffe
+
+data ConsoleEvent
+ = ControlC
+ | Break
+ | Close
+ -- these are sent to Services only.
+ | Logoff
+ | Shutdown
+ deriving (Eq, Ord, Enum, Show, Read, Typeable)
+
+start_console_handler :: Word32 -> IO ()
+start_console_handler r =
+ case toWin32ConsoleEvent r of
+ Just x -> withMVar win32ConsoleHandler $ \handler -> do
+ forkIO (handler x)
+ return ()
+ Nothing -> return ()
+
+toWin32ConsoleEvent :: Num a => a -> Maybe ConsoleEvent
+toWin32ConsoleEvent ev =
+ case ev of
+ 0 {- CTRL_C_EVENT-} -> Just ControlC
+ 1 {- CTRL_BREAK_EVENT-} -> Just Break
+ 2 {- CTRL_CLOSE_EVENT-} -> Just Close
+ 5 {- CTRL_LOGOFF_EVENT-} -> Just Logoff
+ 6 {- CTRL_SHUTDOWN_EVENT-} -> Just Shutdown
+ _ -> Nothing
+
+win32ConsoleHandler :: MVar (ConsoleEvent -> IO ())
+win32ConsoleHandler = unsafePerformIO (newMVar (error "win32ConsoleHandler"))
+
+-- XXX Is this actually needed?
+stick :: IORef HANDLE
+{-# NOINLINE stick #-}
+stick = unsafePerformIO (newIORef nullPtr)
+
+wakeupIOManager :: IO ()
+wakeupIOManager = do
+ _hdl <- readIORef stick
+ c_sendIOManagerEvent io_MANAGER_WAKEUP
+
+-- Walk the queue of pending delays, waking up any that have passed
+-- and return the smallest delay to wait for. The queue of pending
+-- delays is kept ordered.
+getDelay :: USecs -> [DelayReq] -> IO ([DelayReq], DWORD)
+getDelay _ [] = return ([], iNFINITE)
+getDelay now all@(d : rest)
+ = case d of
+ Delay time m | now >= time -> do
+ putMVar m ()
+ getDelay now rest
+ DelaySTM time t | now >= time -> do
+ atomically $ writeTVar t True
+ getDelay now rest
+ _otherwise ->
+ -- delay is in millisecs for WaitForSingleObject
+ let micro_seconds = delayTime d - now
+ milli_seconds = (micro_seconds + 999) `div` 1000
+ in return (all, fromIntegral milli_seconds)
+
+-- ToDo: this just duplicates part of System.Win32.Types, which isn't
+-- available yet. We should move some Win32 functionality down here,
+-- maybe as part of the grand reorganisation of the base package...
+type HANDLE = Ptr ()
+type DWORD = Word32
+
+iNFINITE :: DWORD
+iNFINITE = 0xFFFFFFFF -- urgh
+
+foreign import ccall unsafe "getIOManagerEvent" -- in the RTS (ThrIOManager.c)
+ c_getIOManagerEvent :: IO HANDLE
+
+foreign import ccall unsafe "readIOManagerEvent" -- in the RTS (ThrIOManager.c)
+ c_readIOManagerEvent :: IO Word32
+
+foreign import ccall unsafe "sendIOManagerEvent" -- in the RTS (ThrIOManager.c)
+ c_sendIOManagerEvent :: Word32 -> IO ()
+
+foreign import ccall unsafe "maperrno" -- in Win32Utils.c
+ c_maperrno :: IO ()
+
+foreign import stdcall "WaitForSingleObject"
+ c_WaitForSingleObject :: HANDLE -> DWORD -> IO DWORD
+
+#else
+-- ----------------------------------------------------------------------------
+-- Unix IO manager thread, using select()
+
+startIOManagerThread :: IO ()
+startIOManagerThread = do
+ allocaArray 2 $ \fds -> do
+ throwErrnoIfMinus1 "startIOManagerThread" (c_pipe fds)
+ rd_end <- peekElemOff fds 0
+ wr_end <- peekElemOff fds 1
+ setNonBlockingFD wr_end -- writes happen in a signal handler, we
+ -- don't want them to block.
+ writeIORef stick (fromIntegral wr_end)
+ c_setIOManagerPipe wr_end
+ forkIO $ do
+ allocaBytes sizeofFdSet $ \readfds -> do
+ allocaBytes sizeofFdSet $ \writefds -> do
+ allocaBytes sizeofTimeVal $ \timeval -> do
+ service_loop (fromIntegral rd_end) readfds writefds timeval [] []
+ return ()
+
+service_loop
+ :: Fd -- listen to this for wakeup calls
+ -> Ptr CFdSet
+ -> Ptr CFdSet
+ -> Ptr CTimeVal
+ -> [IOReq]
+ -> [DelayReq]
+ -> IO ()
+service_loop wakeup readfds writefds ptimeval old_reqs old_delays = do
+
+ -- pick up new IO requests
+ new_reqs <- atomicModifyIORef pendingEvents (\a -> ([],a))
+ let reqs = new_reqs ++ old_reqs
+
+ -- pick up new delay requests
+ new_delays <- atomicModifyIORef pendingDelays (\a -> ([],a))
+ let delays0 = foldr insertDelay old_delays new_delays
+
+ -- build the FDSets for select()
+ fdZero readfds
+ fdZero writefds
+ fdSet wakeup readfds
+ maxfd <- buildFdSets 0 readfds writefds reqs
+
+ -- perform the select()
+ let do_select delays = do
+ -- check the current time and wake up any thread in
+ -- threadDelay whose timeout has expired. Also find the
+ -- timeout value for the select() call.
+ now <- getUSecOfDay
+ (delays', timeout) <- getDelay now ptimeval delays
+
+ res <- c_select (fromIntegral ((max wakeup maxfd)+1)) readfds writefds
+ nullPtr timeout
+ if (res == -1)
+ then do
+ err <- getErrno
+ case err of
+ _ | err == eINTR -> do_select delays'
+ -- EINTR: just redo the select()
+ _ | err == eBADF -> return (True, delays)
+ -- EBADF: one of the file descriptors is closed or bad,
+ -- we don't know which one, so wake everyone up.
+ _ | otherwise -> throwErrno "select"
+ -- otherwise (ENOMEM or EINVAL) something has gone
+ -- wrong; report the error.
+ else
+ return (False,delays')
+
+ (wakeup_all,delays') <- do_select delays0
+
+ exit <-
+ if wakeup_all then return False
+ else do
+ b <- fdIsSet wakeup readfds
+ if b == 0
+ then return False
+ else alloca $ \p -> do
+ c_read (fromIntegral wakeup) p 1
+ s <- peek p
+ case s of
+ _ | s == io_MANAGER_WAKEUP -> return False
+ _ | s == io_MANAGER_DIE -> return True
+ _ | s == io_MANAGER_SYNC -> do
+ mvars <- readIORef sync
+ mapM_ (flip putMVar ()) mvars
+ return False
+ _ -> do
+ fp <- mallocForeignPtrBytes (fromIntegral sizeof_siginfo_t)
+ withForeignPtr fp $ \p_siginfo -> do
+ r <- c_read (fromIntegral wakeup) (castPtr p_siginfo)
+ sizeof_siginfo_t
+ when (r /= fromIntegral sizeof_siginfo_t) $
+ error "failed to read siginfo_t"
+ runHandlers' fp (fromIntegral s)
+ return False
+
+ if exit then return () else do
+
+ atomicModifyIORef prodding (\_ -> (False,False))
+
+ reqs' <- if wakeup_all then do wakeupAll reqs; return []
+ else completeRequests reqs readfds writefds []
+
+ service_loop wakeup readfds writefds ptimeval reqs' delays'
+
+io_MANAGER_WAKEUP, io_MANAGER_DIE, io_MANAGER_SYNC :: CChar
+io_MANAGER_WAKEUP = 0xff
+io_MANAGER_DIE = 0xfe
+io_MANAGER_SYNC = 0xfd
+
+-- | the stick is for poking the IO manager with
+stick :: IORef Fd
+{-# NOINLINE stick #-}
+stick = unsafePerformIO (newIORef 0)
+
+{-# NOINLINE sync #-}
+sync :: IORef [MVar ()]
+sync = unsafePerformIO (newIORef [])
+
+-- waits for the IO manager to drain the pipe
+syncIOManager :: IO ()
+syncIOManager = do
+ m <- newEmptyMVar
+ atomicModifyIORef sync (\old -> (m:old,()))
+ fd <- readIORef stick
+ with io_MANAGER_SYNC $ \pbuf -> do
+ c_write (fromIntegral fd) pbuf 1; return ()
+ takeMVar m
+
+wakeupIOManager :: IO ()
+wakeupIOManager = do
+ fd <- readIORef stick
+ with io_MANAGER_WAKEUP $ \pbuf -> do
+ c_write (fromIntegral fd) pbuf 1; return ()
+
+-- For the non-threaded RTS
+runHandlers :: Ptr Word8 -> Int -> IO ()
+runHandlers p_info sig = do
+ fp <- mallocForeignPtrBytes (fromIntegral sizeof_siginfo_t)
+ withForeignPtr fp $ \p -> do
+ copyBytes p p_info (fromIntegral sizeof_siginfo_t)
+ free p_info
+ runHandlers' fp (fromIntegral sig)
+
+runHandlers' :: ForeignPtr Word8 -> Signal -> IO ()
+runHandlers' p_info sig = do
+ let int = fromIntegral sig
+ withMVar signal_handlers $ \arr ->
+ if not (inRange (boundsIOArray arr) int)
+ then return ()
+ else do handler <- unsafeReadIOArray arr int
+ case handler of
+ Nothing -> return ()
+ Just (f,_) -> do forkIO (f p_info); return ()
+
+foreign import ccall "setIOManagerPipe"
+ c_setIOManagerPipe :: CInt -> IO ()
+
+foreign import ccall "__hscore_sizeof_siginfo_t"
+ sizeof_siginfo_t :: CSize
+
+type Signal = CInt
+
+maxSig = 64 :: Int
+
+type HandlerFun = ForeignPtr Word8 -> IO ()
+
+-- Lock used to protect concurrent access to signal_handlers. Symptom of
+-- this race condition is #1922, although that bug was on Windows a similar
+-- bug also exists on Unix.
+{-# NOINLINE signal_handlers #-}
+signal_handlers :: MVar (IOArray Int (Maybe (HandlerFun,Dynamic)))
+signal_handlers = unsafePerformIO $ do
+ arr <- newIOArray (0,maxSig) Nothing
+ newMVar arr
+
+setHandler :: Signal -> Maybe (HandlerFun,Dynamic) -> IO (Maybe (HandlerFun,Dynamic))
+setHandler sig handler = do
+ let int = fromIntegral sig
+ withMVar signal_handlers $ \arr ->
+ if not (inRange (boundsIOArray arr) int)
+ then error "GHC.Conc.setHandler: signal out of range"
+ else do old <- unsafeReadIOArray arr int
+ unsafeWriteIOArray arr int handler
+ return old
+
+-- -----------------------------------------------------------------------------
+-- IO requests
+
+buildFdSets :: Fd -> Ptr CFdSet -> Ptr CFdSet -> [IOReq] -> IO Fd
+buildFdSets maxfd _ _ [] = return maxfd
+buildFdSets maxfd readfds writefds (Read fd _ : reqs)
+ | fd >= fD_SETSIZE = error "buildFdSets: file descriptor out of range"
+ | otherwise = do
+ fdSet fd readfds
+ buildFdSets (max maxfd fd) readfds writefds reqs
+buildFdSets maxfd readfds writefds (Write fd _ : reqs)
+ | fd >= fD_SETSIZE = error "buildFdSets: file descriptor out of range"
+ | otherwise = do
+ fdSet fd writefds
+ buildFdSets (max maxfd fd) readfds writefds reqs
+
+completeRequests :: [IOReq] -> Ptr CFdSet -> Ptr CFdSet -> [IOReq]
+ -> IO [IOReq]
+completeRequests [] _ _ reqs' = return reqs'
+completeRequests (Read fd m : reqs) readfds writefds reqs' = do
+ b <- fdIsSet fd readfds
+ if b /= 0
+ then do putMVar m (); completeRequests reqs readfds writefds reqs'
+ else completeRequests reqs readfds writefds (Read fd m : reqs')
+completeRequests (Write fd m : reqs) readfds writefds reqs' = do
+ b <- fdIsSet fd writefds
+ if b /= 0
+ then do putMVar m (); completeRequests reqs readfds writefds reqs'
+ else completeRequests reqs readfds writefds (Write fd m : reqs')
+
+wakeupAll :: [IOReq] -> IO ()
+wakeupAll [] = return ()
+wakeupAll (Read _ m : reqs) = do putMVar m (); wakeupAll reqs
+wakeupAll (Write _ m : reqs) = do putMVar m (); wakeupAll reqs
+
+waitForReadEvent :: Fd -> IO ()
+waitForReadEvent fd = do
+ m <- newEmptyMVar
+ atomicModifyIORef pendingEvents (\xs -> (Read fd m : xs, ()))
+ prodServiceThread
+ takeMVar m
+
+waitForWriteEvent :: Fd -> IO ()
+waitForWriteEvent fd = do
+ m <- newEmptyMVar
+ atomicModifyIORef pendingEvents (\xs -> (Write fd m : xs, ()))
+ prodServiceThread
+ takeMVar m
+
+-- -----------------------------------------------------------------------------
+-- Delays
+
+-- Walk the queue of pending delays, waking up any that have passed
+-- and return the smallest delay to wait for. The queue of pending
+-- delays is kept ordered.
+getDelay :: USecs -> Ptr CTimeVal -> [DelayReq] -> IO ([DelayReq], Ptr CTimeVal)
+getDelay _ _ [] = return ([],nullPtr)
+getDelay now ptimeval all@(d : rest)
+ = case d of
+ Delay time m | now >= time -> do
+ putMVar m ()
+ getDelay now ptimeval rest
+ DelaySTM time t | now >= time -> do
+ atomically $ writeTVar t True
+ getDelay now ptimeval rest
+ _otherwise -> do
+ setTimevalTicks ptimeval (delayTime d - now)
+ return (all,ptimeval)
+
+data CTimeVal
+
+foreign import ccall unsafe "sizeofTimeVal"
+ sizeofTimeVal :: Int
+
+foreign import ccall unsafe "setTimevalTicks"
+ setTimevalTicks :: Ptr CTimeVal -> USecs -> IO ()
+
+{-
+ On Win32 we're going to have a single Pipe, and a
+ waitForSingleObject with the delay time. For signals, we send a
+ byte down the pipe just like on Unix.
+-}
+
+-- ----------------------------------------------------------------------------
+-- select() interface
+
+-- ToDo: move to System.Posix.Internals?
+
+data CFdSet
+
+foreign import ccall safe "select"
+ c_select :: CInt -> Ptr CFdSet -> Ptr CFdSet -> Ptr CFdSet -> Ptr CTimeVal
+ -> IO CInt
+
+foreign import ccall unsafe "hsFD_SETSIZE"
+ c_fD_SETSIZE :: CInt
+
+fD_SETSIZE :: Fd
+fD_SETSIZE = fromIntegral c_fD_SETSIZE
+
+foreign import ccall unsafe "hsFD_ISSET"
+ c_fdIsSet :: CInt -> Ptr CFdSet -> IO CInt
+
+fdIsSet :: Fd -> Ptr CFdSet -> IO CInt
+fdIsSet (Fd fd) fdset = c_fdIsSet fd fdset
+
+foreign import ccall unsafe "hsFD_SET"
+ c_fdSet :: CInt -> Ptr CFdSet -> IO ()
+
+fdSet :: Fd -> Ptr CFdSet -> IO ()
+fdSet (Fd fd) fdset = c_fdSet fd fdset
+
+foreign import ccall unsafe "hsFD_ZERO"
+ fdZero :: Ptr CFdSet -> IO ()
+
+foreign import ccall unsafe "sizeof_fd_set"
+ sizeofFdSet :: Int
+
+#endif
+
+reportStackOverflow :: IO a
+reportStackOverflow = do callStackOverflowHook; return undefined
+
+reportError :: SomeException -> IO a
+reportError ex = do
+ handler <- getUncaughtExceptionHandler
+ handler ex
+ return undefined
+
+-- SUP: Are the hooks allowed to re-enter Haskell land? If so, remove
+-- the unsafe below.
+foreign import ccall unsafe "stackOverflow"
+ callStackOverflowHook :: IO ()
+
+{-# NOINLINE uncaughtExceptionHandler #-}
+uncaughtExceptionHandler :: IORef (SomeException -> IO ())
+uncaughtExceptionHandler = unsafePerformIO (newIORef defaultHandler)
+ where
+ defaultHandler :: SomeException -> IO ()
+ defaultHandler se@(SomeException ex) = do
+ (hFlush stdout) `catchAny` (\ _ -> return ())
+ let msg = case cast ex of
+ Just Deadlock -> "no threads to run: infinite loop or deadlock?"
+ _ -> case cast ex of
+ Just (ErrorCall s) -> s
+ _ -> showsPrec 0 se ""
+ withCString "%s" $ \cfmt ->
+ withCString msg $ \cmsg ->
+ errorBelch cfmt cmsg
+
+-- don't use errorBelch() directly, because we cannot call varargs functions
+-- using the FFI.
+foreign import ccall unsafe "HsBase.h errorBelch2"
+ errorBelch :: CString -> CString -> IO ()
+
+setUncaughtExceptionHandler :: (SomeException -> IO ()) -> IO ()
+setUncaughtExceptionHandler = writeIORef uncaughtExceptionHandler
+
+getUncaughtExceptionHandler :: IO (SomeException -> IO ())
+getUncaughtExceptionHandler = readIORef uncaughtExceptionHandler
+
+
+withMVar :: MVar a -> (a -> IO b) -> IO b
+withMVar m io =
+ block $ do
+ a <- takeMVar m
+ b <- catchAny (unblock (io a))
+ (\e -> do putMVar m a; throw e)
+ putMVar m a
+ return b
\end{code}
projects / ghc-base.git / blobdiff