[project @ 2001-08-04 06:19:54 by ken]

[ghc-hetmet.git] / ghc / lib / std / PrelConc.lhs

diff --git a/ghc/lib/std/PrelConc.lhs b/ghc/lib/std/PrelConc.lhs
index d75bbca..0ffe3a9 100644 (file)
--- a/ghc/lib/std/PrelConc.lhs
+++ b/ghc/lib/std/PrelConc.lhs
@@ -1,5 +1,7 @@
+% -----------------------------------------------------------------------------
+% $Id: PrelConc.lhs,v 1.24 2001/05/18 16:54:05 simonmar Exp $
 %
-% (c) The AQUA Project, Glasgow University, 1994-1996
+% (c) The University of Glasgow, 1994-2000
 %
 
 \section[PrelConc]{Module @PrelConc@}
@@ -7,7 +9,7 @@
 Basic concurrency stuff
 
 \begin{code}
-{-# OPTIONS -fcompiling-prelude -fno-implicit-prelude #-}
+{-# OPTIONS -fno-implicit-prelude #-}
 
 module PrelConc
        ( ThreadId(..)
@@ -15,7 +17,7 @@ module PrelConc
        -- Forking and suchlike
        , myThreadId    -- :: IO ThreadId
        , killThread    -- :: ThreadId -> IO ()
-       , raiseInThread -- :: ThreadId -> Exception -> IO ()
+       , throwTo       -- :: ThreadId -> Exception -> IO ()
        , par           -- :: a -> b -> b
        , seq           -- :: a -> b -> b
        , yield         -- :: IO ()
@@ -31,18 +33,17 @@ module PrelConc
        , newEmptyMVar  -- :: IO (MVar a)
        , takeMVar      -- :: MVar a -> IO a
        , putMVar       -- :: MVar a -> a -> IO ()
-       , readMVar      -- :: MVar a -> IO a
-       , swapMVar      -- :: MVar a -> a -> IO a
-       , takeMaybeMVar -- :: MVar a -> IO (Maybe a)
+       , tryTakeMVar   -- :: MVar a -> IO (Maybe a)
+       , tryPutMVar    -- :: MVar a -> a -> IO Bool
        , isEmptyMVar   -- :: MVar a -> IO Bool
+       , addMVarFinalizer -- :: MVar a -> IO () -> IO ()
 
     ) where
 
 import PrelBase
 import PrelMaybe
-import PrelErr ( parError, seqError )
-import PrelST          ( liftST )
-import PrelIOBase      ( IO(..), MVar(..), unsafePerformIO )
+import PrelErr         ( parError, seqError )
+import PrelIOBase      ( IO(..), MVar(..) )
 import PrelBase                ( Int(..) )
 import PrelException    ( Exception(..), AsyncException(..) )
 
@@ -67,8 +68,8 @@ killThread :: ThreadId -> IO ()
 killThread (ThreadId id) = IO $ \ s ->
    case (killThread# id (AsyncException ThreadKilled) s) of s1 -> (# s1, () #)
 
-raiseInThread :: ThreadId -> Exception -> IO ()
-raiseInThread (ThreadId id) ex = IO $ \ s ->
+throwTo :: ThreadId -> Exception -> IO ()
+throwTo (ThreadId id) ex = IO $ \ s ->
    case (killThread# id ex s) of s1 -> (# s1, () #)
 
 myThreadId :: IO ThreadId
@@ -79,7 +80,7 @@ yield :: IO ()
 yield = IO $ \s -> 
    case (yield# s) of s1 -> (# s1, () #)
 
--- "seq" is defined a bit wierdly (see below)
+-- "seq" is defined a bit weirdly (see below)
 --
 -- The reason for the strange "0# -> parError" case is that
 -- it fools the compiler into thinking that seq is non-strict in
@@ -129,28 +130,22 @@ putMVar (MVar mvar#) x = IO $ \ s# ->
     case putMVar# mvar# x s# of
         s2# -> (# s2#, () #)
 
+tryPutMVar  :: MVar a -> a -> IO Bool
+tryPutMVar (MVar mvar#) x = IO $ \ s# ->
+    case tryPutMVar# mvar# x s# of
+        (# s, 0# #) -> (# s, False #)
+        (# s, _  #) -> (# s, True #)
+
 newMVar :: a -> IO (MVar a)
 newMVar value =
     newEmptyMVar       >>= \ mvar ->
     putMVar mvar value >>
     return mvar
 
-readMVar :: MVar a -> IO a
-readMVar mvar =
-    takeMVar mvar      >>= \ value ->
-    putMVar mvar value >>
-    return value
-
-swapMVar :: MVar a -> a -> IO a
-swapMVar mvar new =
-    takeMVar mvar      >>= \ old ->
-    putMVar mvar new   >>
-    return old
-
--- takeMaybeMVar is a non-blocking takeMVar
-takeMaybeMVar :: MVar a -> IO (Maybe a)
-takeMaybeMVar (MVar m) = IO $ \ s ->
-    case takeMaybeMVar# m s of
+-- tryTakeMVar is a non-blocking takeMVar
+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
 
@@ -161,7 +156,7 @@ takeMaybeMVar (MVar m) = IO $ \ s ->
  the MVar may have been filled (or emptied) - so be extremely
  careful when using this operation.  
 
- Use takeMaybeMVar instead if possible.
+ Use tryTakeMVar instead if possible.
 
  If you can re-work your abstractions to avoid having to
  depend on isEmptyMVar, then you're encouraged to do so,
@@ -172,6 +167,11 @@ isEmptyMVar :: MVar a -> IO Bool
 isEmptyMVar (MVar mv#) = IO $ \ s# -> 
     case isEmptyMVar# mv# s# of
         (# s2#, flg #) -> (# s2#, not (flg ==# 0#) #)
+
+-- Like addForeignPtrFinalizer, but for MVars
+addMVarFinalizer :: MVar a -> IO () -> IO ()
+addMVarFinalizer (MVar m) finalizer = 
+  IO $ \s -> case mkWeak# m () finalizer s of { (# s1, w #) -> (# s1, () #) }
 \end{code}