add numSparks :: IO Int (#4167)

[ghc-base.git] / GHC / Conc.lhs

diff --git a/GHC/Conc.lhs b/GHC/Conc.lhs
index 715e569..0d17457 100644 (file)
--- a/GHC/Conc.lhs
+++ b/GHC/Conc.lhs
@@ -29,8 +29,11 @@ module GHC.Conc
 
         -- * Forking and suchlike
         , forkIO        -- :: IO a -> IO ThreadId
 
         -- * Forking and suchlike
         , forkIO        -- :: IO a -> IO ThreadId

+        , forkIOUnmasked

         , forkOnIO      -- :: Int -> IO a -> IO ThreadId
         , forkOnIO      -- :: Int -> IO a -> IO ThreadId

+        , forkOnIOUnmasked

         , numCapabilities -- :: Int
         , numCapabilities -- :: Int

+        , numSparks      -- :: IO Int

         , childHandler  -- :: Exception -> IO ()
         , myThreadId    -- :: IO ThreadId
         , killThread    -- :: ThreadId -> IO ()
         , childHandler  -- :: Exception -> IO ()
         , myThreadId    -- :: IO ThreadId
         , killThread    -- :: ThreadId -> IO ()

@@ -211,8 +214,8 @@ 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.
 
 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').
+GHC note: the new thread inherits the /masked/ state of the parent 
+(see 'Control.Exception.mask').

 
 The newly created thread has an exception handler that discards the
 exceptions 'BlockedIndefinitelyOnMVar', 'BlockedIndefinitelyOnSTM', and
 
 The newly created thread has an exception handler that discards the
 exceptions 'BlockedIndefinitelyOnMVar', 'BlockedIndefinitelyOnSTM', and

@@ -225,6 +228,11 @@ forkIO action = IO $ \ s ->
  where
   action_plus = catchException action childHandler
 
  where
   action_plus = catchException action childHandler
 

+-- | Like 'forkIO', but the child thread is created with asynchronous exceptions
+-- unmasked (see 'Control.Exception.mask').
+forkIOUnmasked :: IO () -> IO ThreadId
+forkIOUnmasked io = forkIO (unsafeUnmask io)
+

 {- |
 Like 'forkIO', but lets you specify on which CPU the thread is
 created.  Unlike a `forkIO` thread, a thread created by `forkOnIO`
 {- |
 Like 'forkIO', but lets you specify on which CPU the thread is
 created.  Unlike a `forkIO` thread, a thread created by `forkOnIO`

@@ -244,6 +252,11 @@ forkOnIO (I# cpu) action = IO $ \ s ->
  where
   action_plus = catchException action childHandler
 
  where
   action_plus = catchException action childHandler
 

+-- | Like 'forkOnIO', but the child thread is created with
+-- asynchronous exceptions unmasked (see 'Control.Exception.mask').
+forkOnIOUnmasked :: Int -> IO () -> IO ThreadId
+forkOnIOUnmasked cpu io = forkOnIO cpu (unsafeUnmask io)
+

 -- | 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 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

@@ -253,6 +266,10 @@ numCapabilities = unsafePerformIO $  do
                     n <- peek n_capabilities
                     return (fromIntegral n)
 
                     n <- peek n_capabilities
                     return (fromIntegral n)
 

+-- | Returns the number of sparks currently in the local spark pool
+numSparks :: IO Int
+numSparks = IO $ \s -> case numSparks# s of (# s', n #) -> (# s', I# n #)
+

 #if defined(mingw32_HOST_OS) && defined(__PIC__)
 foreign import ccall "_imp__n_capabilities" n_capabilities :: Ptr CInt
 #else
 #if defined(mingw32_HOST_OS) && defined(__PIC__)
 foreign import ccall "_imp__n_capabilities" n_capabilities :: Ptr CInt
 #else

@@ -301,7 +318,7 @@ another 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
 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.
+the call is inside a 'mask' or not.

 
 Important note: the behaviour of 'throwTo' differs from that described in
 the paper \"Asynchronous exceptions in Haskell\"
 
 Important note: the behaviour of 'throwTo' differs from that described in
 the paper \"Asynchronous exceptions in Haskell\"

@@ -310,7 +327,8 @@ 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
 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).
+the paper).  Unlike other interruptible operations, however, 'throwTo'
+is /always/ interruptible, even if it does not actually block.

 
 There is no guarantee that the exception will be delivered promptly,
 although the runtime will endeavour to ensure that arbitrary
 
 There is no guarantee that the exception will be delivered promptly,
 although the runtime will endeavour to ensure that arbitrary

@@ -476,6 +494,10 @@ thenSTM (STM m) k = STM ( \s ->
 returnSTM :: a -> STM a
 returnSTM x = STM (\s -> (# s, x #))
 
 returnSTM :: a -> STM a
 returnSTM x = STM (\s -> (# s, x #))
 

+instance MonadPlus STM where
+  mzero = retry
+  mplus = orElse
+

 -- | Unsafely performs IO in the STM monad.  Beware: this is a highly
 -- dangerous thing to do.  
 --
 -- | Unsafely performs IO in the STM monad.  Beware: this is a highly
 -- dangerous thing to do.  
 --

@@ -606,18 +628,18 @@ MVar utilities
 \begin{code}
 withMVar :: MVar a -> (a -> IO b) -> IO b
 withMVar m io = 
 \begin{code}
 withMVar :: MVar a -> (a -> IO b) -> IO b
 withMVar m io = 

-  block $ do
+  mask $ \restore -> do

     a <- takeMVar m
     a <- takeMVar m

-    b <- catchAny (unblock (io a))
+    b <- catchAny (restore (io a))

             (\e -> do putMVar m a; throw e)
     putMVar m a
     return b
 
 modifyMVar_ :: MVar a -> (a -> IO a) -> IO ()
 modifyMVar_ m io =
             (\e -> do putMVar m a; throw e)
     putMVar m a
     return b
 
 modifyMVar_ :: MVar a -> (a -> IO a) -> IO ()
 modifyMVar_ m io =

-  block $ do
+  mask $ \restore -> do

     a <- takeMVar m
     a <- takeMVar m

-    a' <- catchAny (unblock (io a))
+    a' <- catchAny (restore (io a))

             (\e -> do putMVar m a; throw e)
     putMVar m a'
     return ()
             (\e -> do putMVar m a; throw e)
     putMVar m a'
     return ()

@@ -856,7 +878,7 @@ prodServiceThread = do
 --
 sharedCAF :: a -> (Ptr a -> IO (Ptr a)) -> IO a
 sharedCAF a get_or_set =
 --
 sharedCAF :: a -> (Ptr a -> IO (Ptr a)) -> IO a
 sharedCAF a get_or_set =

-   block $ do
+   mask_ $ do

      stable_ref <- newStablePtr a
      let ref = castPtr (castStablePtrToPtr stable_ref)
      ref2 <- get_or_set ref
      stable_ref <- newStablePtr a
      let ref = castPtr (castStablePtrToPtr stable_ref)
      ref2 <- get_or_set ref