content: {-# LANGUAGE Trustworthy #-}
  {-# LANGUAGE CPP, NoImplicitPrelude #-}
  
  -----------------------------------------------------------------------------
  -- |
  -- Module      :  Foreign.Concurrent
  -- Copyright   :  (c) The University of Glasgow 2003
  -- License     :  BSD-style (see the file libraries/base/LICENSE)
  -- 
  -- Maintainer  :  ffi@haskell.org
  -- Stability   :  provisional
  -- Portability :  non-portable (requires concurrency)
  --
  -- FFI datatypes and operations that use or require concurrency (GHC only).
  --
  -----------------------------------------------------------------------------
  
  module Foreign.Concurrent
    (
          -- * Concurrency-based 'ForeignPtr' operations
  
          -- | These functions generalize their namesakes in the portable
          -- "Foreign.ForeignPtr" module by allowing arbitrary 'IO' actions
          -- as finalizers.  These finalizers necessarily run in a separate
          -- thread, cf. /Destructors, Finalizers and Synchronization/,
          -- by Hans Boehm, /POPL/, 2003.
  
          newForeignPtr,
          addForeignPtrFinalizer,
    ) where
  
  #ifdef __GLASGOW_HASKELL__
  import GHC.IO         ( IO )
  import GHC.Ptr        ( Ptr )
  import GHC.ForeignPtr ( ForeignPtr )
  import qualified GHC.ForeignPtr
  
  newForeignPtr :: Ptr a -> IO () -> IO (ForeignPtr a)
  -- ^Turns a plain memory reference into a foreign object by associating
  -- a finalizer - given by the monadic operation - with the reference.
  -- The finalizer will be executed after the last reference to the
  -- foreign object is dropped.  There is no guarantee of promptness, and
  -- in fact there is no guarantee that the finalizer will eventually
  -- run at all.
  newForeignPtr = GHC.ForeignPtr.newConcForeignPtr
  
  addForeignPtrFinalizer :: ForeignPtr a -> IO () -> IO ()
  -- ^This function adds a finalizer to the given 'ForeignPtr'.
  -- The finalizer will run after the last reference to the foreign object
  -- is dropped, but /before/ all previously registered finalizers for the
  -- same object.
  addForeignPtrFinalizer = GHC.ForeignPtr.addForeignPtrConcFinalizer
  #endif
  
  