X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=GHC%2FForeignPtr.hs;h=dbf6c2c180597ed260f7710205d286be3a3ff1fa;hb=7a97ec4b12e1fbec5505f82032cf4dc435b5a60c;hp=c9217ef83626297fcf48b99e8aca82eaebb35e84;hpb=d968106fdef283b30d06ae45fa2f87329e1c2269;p=ghc-base.git diff --git a/GHC/ForeignPtr.hs b/GHC/ForeignPtr.hs index c9217ef..dbf6c2c 100644 --- a/GHC/ForeignPtr.hs +++ b/GHC/ForeignPtr.hs @@ -1,4 +1,12 @@ -{-# OPTIONS_GHC -fno-implicit-prelude #-} +{-# LANGUAGE CPP + , NoImplicitPrelude + , BangPatterns + , MagicHash + , UnboxedTuples + #-} +{-# OPTIONS_HADDOCK hide #-} +{-# LANGUAGE DeriveDataTypeable, StandaloneDeriving #-} + ----------------------------------------------------------------------------- -- | -- Module : GHC.ForeignPtr @@ -16,31 +24,37 @@ -- #hide module GHC.ForeignPtr ( - ForeignPtr(..), - FinalizerPtr, - newForeignPtr_, - mallocForeignPtr, - mallocForeignPtrBytes, - addForeignPtrFinalizer, - touchForeignPtr, - unsafeForeignPtrToPtr, - castForeignPtr, - newConcForeignPtr, - addForeignPtrConcFinalizer, - finalizeForeignPtr + ForeignPtr(..), + FinalizerPtr, + FinalizerEnvPtr, + newForeignPtr_, + mallocForeignPtr, + mallocPlainForeignPtr, + mallocForeignPtrBytes, + mallocPlainForeignPtrBytes, + addForeignPtrFinalizer, + addForeignPtrFinalizerEnv, + touchForeignPtr, + unsafeForeignPtrToPtr, + castForeignPtr, + newConcForeignPtr, + addForeignPtrConcFinalizer, + finalizeForeignPtr ) where -import Control.Monad ( sequence_ ) -import Foreign.Ptr +import Control.Monad ( sequence_ ) import Foreign.Storable +import Data.Typeable -import GHC.List ( null ) +import GHC.Show +import GHC.List ( null ) import GHC.Base -import GHC.IOBase -import GHC.STRef ( STRef(..) ) -import GHC.Ptr ( Ptr(..) ) +import GHC.IORef +import GHC.STRef ( STRef(..) ) +import GHC.Ptr ( Ptr(..), FunPtr(..) ) import GHC.Err -import GHC.Show + +#include "Typeable.h" -- |The type 'ForeignPtr' represents references to objects that are -- maintained in a foreign language, i.e., that are not part of the @@ -59,19 +73,28 @@ import GHC.Show -- class 'Storable'. -- data ForeignPtr a = ForeignPtr Addr# ForeignPtrContents - -- we cache the Addr# in the ForeignPtr object, but attach - -- the finalizer to the IORef (or the MutableByteArray# in - -- the case of a MallocPtr). The aim of the representation - -- is to make withForeignPtr efficient; in fact, withForeignPtr - -- should be just as efficient as unpacking a Ptr, and multiple - -- withForeignPtrs can share an unpacked ForeignPtr. Note - -- that touchForeignPtr only has to touch the ForeignPtrContents - -- object, because that ensures that whatever the finalizer is - -- attached to is kept alive. - -data ForeignPtrContents - = PlainForeignPtr !(IORef [IO ()]) - | MallocPtr (MutableByteArray# RealWorld) !(IORef [IO ()]) + -- we cache the Addr# in the ForeignPtr object, but attach + -- the finalizer to the IORef (or the MutableByteArray# in + -- the case of a MallocPtr). The aim of the representation + -- is to make withForeignPtr efficient; in fact, withForeignPtr + -- should be just as efficient as unpacking a Ptr, and multiple + -- withForeignPtrs can share an unpacked ForeignPtr. Note + -- that touchForeignPtr only has to touch the ForeignPtrContents + -- object, because that ensures that whatever the finalizer is + -- attached to is kept alive. + +INSTANCE_TYPEABLE1(ForeignPtr,foreignPtrTc,"ForeignPtr") + +data Finalizers + = NoFinalizers + | CFinalizers + | HaskellFinalizers + deriving Eq + +data ForeignPtrContents + = PlainForeignPtr !(IORef (Finalizers, [IO ()])) + | MallocPtr (MutableByteArray# RealWorld) !(IORef (Finalizers, [IO ()])) + | PlainPtr (MutableByteArray# RealWorld) instance Eq (ForeignPtr a) where p == q = unsafeForeignPtrToPtr p == unsafeForeignPtrToPtr q @@ -82,11 +105,13 @@ instance Ord (ForeignPtr a) where instance Show (ForeignPtr a) where showsPrec p f = showsPrec p (unsafeForeignPtrToPtr f) --- |A Finalizer is represented as a pointer to a foreign function that, at + +-- |A finalizer is represented as a pointer to a foreign function that, at -- finalisation time, gets as an argument a plain pointer variant of the -- foreign pointer that the finalizer is associated with. -- -type FinalizerPtr a = FunPtr (Ptr a -> IO ()) +type FinalizerPtr a = FunPtr (Ptr a -> IO ()) +type FinalizerEnvPtr env a = FunPtr (Ptr env -> Ptr a -> IO ()) newConcForeignPtr :: Ptr a -> IO () -> IO (ForeignPtr a) -- @@ -131,33 +156,109 @@ mallocForeignPtr :: Storable a => IO (ForeignPtr a) -- mallocForeignPtr = doMalloc undefined where doMalloc :: Storable b => b -> IO (ForeignPtr b) - doMalloc a = do - r <- newIORef [] - IO $ \s -> - case newPinnedByteArray# size s of { (# s, mbarr# #) -> - (# s, ForeignPtr (byteArrayContents# (unsafeCoerce# mbarr#)) - (MallocPtr mbarr# r) #) + doMalloc a + | I# size < 0 = error "mallocForeignPtr: size must be >= 0" + | otherwise = do + r <- newIORef (NoFinalizers, []) + IO $ \s -> + case newAlignedPinnedByteArray# size align s of { (# s', mbarr# #) -> + (# s', ForeignPtr (byteArrayContents# (unsafeCoerce# mbarr#)) + (MallocPtr mbarr# r) #) } - where (I# size) = sizeOf a + where !(I# size) = sizeOf a + !(I# align) = alignment a -- | This function is similar to 'mallocForeignPtr', except that the -- size of the memory required is given explicitly as a number of bytes. mallocForeignPtrBytes :: Int -> IO (ForeignPtr a) +mallocForeignPtrBytes size | size < 0 = + error "mallocForeignPtrBytes: size must be >= 0" mallocForeignPtrBytes (I# size) = do - r <- newIORef [] + r <- newIORef (NoFinalizers, []) IO $ \s -> - case newPinnedByteArray# size s of { (# s, mbarr# #) -> - (# s, ForeignPtr (byteArrayContents# (unsafeCoerce# mbarr#)) - (MallocPtr mbarr# r) #) + case newPinnedByteArray# size s of { (# s', mbarr# #) -> + (# s', ForeignPtr (byteArrayContents# (unsafeCoerce# mbarr#)) + (MallocPtr mbarr# r) #) + } + +-- | Allocate some memory and return a 'ForeignPtr' to it. The memory +-- will be released automatically when the 'ForeignPtr' is discarded. +-- +-- GHC notes: 'mallocPlainForeignPtr' has a heavily optimised +-- implementation in GHC. It uses pinned memory in the garbage +-- collected heap, as for mallocForeignPtr. Unlike mallocForeignPtr, a +-- ForeignPtr created with mallocPlainForeignPtr carries no finalizers. +-- It is not possible to add a finalizer to a ForeignPtr created with +-- mallocPlainForeignPtr. This is useful for ForeignPtrs that will live +-- only inside Haskell (such as those created for packed strings). +-- Attempts to add a finalizer to a ForeignPtr created this way, or to +-- finalize such a pointer, will throw an exception. +-- +mallocPlainForeignPtr :: Storable a => IO (ForeignPtr a) +mallocPlainForeignPtr = doMalloc undefined + where doMalloc :: Storable b => b -> IO (ForeignPtr b) + doMalloc a + | I# size < 0 = error "mallocForeignPtr: size must be >= 0" + | otherwise = IO $ \s -> + case newAlignedPinnedByteArray# size align s of { (# s', mbarr# #) -> + (# s', ForeignPtr (byteArrayContents# (unsafeCoerce# mbarr#)) + (PlainPtr mbarr#) #) + } + where !(I# size) = sizeOf a + !(I# align) = alignment a + +-- | This function is similar to 'mallocForeignPtrBytes', except that +-- the internally an optimised ForeignPtr representation with no +-- finalizer is used. Attempts to add a finalizer will cause an +-- exception to be thrown. +mallocPlainForeignPtrBytes :: Int -> IO (ForeignPtr a) +mallocPlainForeignPtrBytes size | size < 0 = + error "mallocPlainForeignPtrBytes: size must be >= 0" +mallocPlainForeignPtrBytes (I# size) = IO $ \s -> + case newPinnedByteArray# size s of { (# s', mbarr# #) -> + (# s', ForeignPtr (byteArrayContents# (unsafeCoerce# mbarr#)) + (PlainPtr mbarr#) #) } addForeignPtrFinalizer :: FinalizerPtr a -> ForeignPtr a -> IO () -- ^This function adds a finalizer to the given foreign object. The -- finalizer will run /before/ all other finalizers for the same -- object which have already been registered. -addForeignPtrFinalizer finalizer fptr = - addForeignPtrConcFinalizer fptr - (mkFinalizer finalizer (unsafeForeignPtrToPtr fptr)) +addForeignPtrFinalizer (FunPtr fp) (ForeignPtr p c) = case c of + PlainForeignPtr r -> f r >> return () + MallocPtr _ r -> f r >> return () + _ -> error "GHC.ForeignPtr: attempt to add a finalizer to a plain pointer" + where + f r = + noMixing CFinalizers r $ + IO $ \s -> + case r of { IORef (STRef r#) -> + case mkWeakForeignEnv# r# () fp p 0# nullAddr# s of { (# s1, w #) -> + (# s1, finalizeForeign w #) }} + +addForeignPtrFinalizerEnv :: + FinalizerEnvPtr env a -> Ptr env -> ForeignPtr a -> IO () +-- ^ Like 'addForeignPtrFinalizerEnv' but allows the finalizer to be +-- passed an additional environment parameter to be passed to the +-- finalizer. The environment passed to the finalizer is fixed by the +-- second argument to 'addForeignPtrFinalizerEnv' +addForeignPtrFinalizerEnv (FunPtr fp) (Ptr ep) (ForeignPtr p c) = case c of + PlainForeignPtr r -> f r >> return () + MallocPtr _ r -> f r >> return () + _ -> error "GHC.ForeignPtr: attempt to add a finalizer to a plain pointer" + where + f r = + noMixing CFinalizers r $ + IO $ \s -> + case r of { IORef (STRef r#) -> + case mkWeakForeignEnv# r# () fp p 1# ep s of { (# s1, w #) -> + (# s1, finalizeForeign w #) }} + +finalizeForeign :: Weak# () -> IO () +finalizeForeign w = IO $ \s -> + case finalizeWeak# w s of + (# s1, 0#, _ #) -> (# s1, () #) + (# s1, _ , f #) -> f s1 addForeignPtrConcFinalizer :: ForeignPtr a -> IO () -> IO () -- ^This function adds a finalizer to the given @ForeignPtr@. The @@ -174,38 +275,49 @@ addForeignPtrConcFinalizer :: ForeignPtr a -> IO () -> IO () -- are finalized objects, so a finalizer should not refer to a 'Handle' -- (including @stdout@, @stdin@ or @stderr@). -- -addForeignPtrConcFinalizer (ForeignPtr a c) finalizer = +addForeignPtrConcFinalizer (ForeignPtr _ c) finalizer = addForeignPtrConcFinalizer_ c finalizer -addForeignPtrConcFinalizer_ f@(PlainForeignPtr r) finalizer = do - fs <- readIORef r - writeIORef r (finalizer : fs) - if (null fs) +addForeignPtrConcFinalizer_ :: ForeignPtrContents -> IO () -> IO () +addForeignPtrConcFinalizer_ (PlainForeignPtr r) finalizer = do + noFinalizers <- noMixing HaskellFinalizers r (return finalizer) + if noFinalizers then IO $ \s -> - case r of { IORef (STRef r#) -> - case mkWeak# r# () (foreignPtrFinalizer r) s of { (# s1, w #) -> - (# s1, () #) }} + case r of { IORef (STRef r#) -> + case mkWeak# r# () (foreignPtrFinalizer r) s of { (# s1, _ #) -> + (# s1, () #) }} else return () -addForeignPtrConcFinalizer_ f@(MallocPtr fo r) finalizer = do - fs <- readIORef r - writeIORef r (finalizer : fs) - if (null fs) +addForeignPtrConcFinalizer_ f@(MallocPtr fo r) finalizer = do + noFinalizers <- noMixing HaskellFinalizers r (return finalizer) + if noFinalizers then IO $ \s -> - case mkWeak# fo () (do foreignPtrFinalizer r; touch f) s of - (# s1, w #) -> (# s1, () #) + case mkWeak# fo () (do foreignPtrFinalizer r; touch f) s of + (# s1, _ #) -> (# s1, () #) else return () -foreign import ccall "dynamic" - mkFinalizer :: FinalizerPtr a -> Ptr a -> IO () +addForeignPtrConcFinalizer_ _ _ = + error "GHC.ForeignPtr: attempt to add a finalizer to plain pointer" -foreignPtrFinalizer :: IORef [IO ()] -> IO () -foreignPtrFinalizer r = do fs <- readIORef r; sequence_ fs +noMixing :: + Finalizers -> IORef (Finalizers, [IO ()]) -> IO (IO ()) -> IO Bool +noMixing ftype0 r mkF = do + (ftype, fs) <- readIORef r + if ftype /= NoFinalizers && ftype /= ftype0 + then error ("GHC.ForeignPtr: attempt to mix Haskell and C finalizers " ++ + "in the same ForeignPtr") + else do + f <- mkF + writeIORef r (ftype0, f : fs) + return (null fs) + +foreignPtrFinalizer :: IORef (Finalizers, [IO ()]) -> IO () +foreignPtrFinalizer r = do (_, fs) <- readIORef r; sequence_ fs newForeignPtr_ :: Ptr a -> IO (ForeignPtr a) -- ^Turns a plain memory reference into a foreign pointer that may be -- associated with finalizers by using 'addForeignPtrFinalizer'. newForeignPtr_ (Ptr obj) = do - r <- newIORef [] + r <- newIORef (NoFinalizers, []) return (ForeignPtr obj (PlainForeignPtr r)) touchForeignPtr :: ForeignPtr a -> IO () @@ -233,9 +345,10 @@ touchForeignPtr :: ForeignPtr a -> IO () -- result in artificial deadlock. Another alternative is to use -- explicit reference counting. -- -touchForeignPtr (ForeignPtr fo r) = touch r +touchForeignPtr (ForeignPtr _ r) = touch r -touch r = IO $ \s -> case touch# r s of s -> (# s, () #) +touch :: ForeignPtrContents -> IO () +touch r = IO $ \s -> case touch# r s of s' -> (# s', () #) unsafeForeignPtrToPtr :: ForeignPtr a -> Ptr a -- ^This function extracts the pointer component of a foreign @@ -250,9 +363,9 @@ unsafeForeignPtrToPtr :: ForeignPtr a -> Ptr a -- To avoid subtle coding errors, hand written marshalling code -- should preferably use 'Foreign.ForeignPtr.withForeignPtr' rather -- than combinations of 'unsafeForeignPtrToPtr' and --- 'touchForeignPtr'. However, the later routines +-- 'touchForeignPtr'. However, the latter routines -- are occasionally preferred in tool generated marshalling code. -unsafeForeignPtrToPtr (ForeignPtr fo r) = Ptr fo +unsafeForeignPtrToPtr (ForeignPtr fo _) = Ptr fo castForeignPtr :: ForeignPtr a -> ForeignPtr b -- ^This function casts a 'ForeignPtr' @@ -262,11 +375,15 @@ castForeignPtr f = unsafeCoerce# f -- | Causes the finalizers associated with a foreign pointer to be run -- immediately. finalizeForeignPtr :: ForeignPtr a -> IO () +finalizeForeignPtr (ForeignPtr _ (PlainPtr _)) = return () -- no effect finalizeForeignPtr (ForeignPtr _ foreignPtr) = do - finalizers <- readIORef refFinalizers - sequence_ finalizers - writeIORef refFinalizers [] - where - refFinalizers = case foreignPtr of - (PlainForeignPtr ref) -> ref - (MallocPtr _ ref) -> ref + (ftype, finalizers) <- readIORef refFinalizers + sequence_ finalizers + writeIORef refFinalizers (ftype, []) + where + refFinalizers = case foreignPtr of + (PlainForeignPtr ref) -> ref + (MallocPtr _ ref) -> ref + PlainPtr _ -> + error "finalizeForeignPtr PlainPtr" +