spawn 0.2 → 0.3

raw patch · 4 files changed

+89/−7 lines, 4 files

Files

• Control/Concurrent/Spawn.hs +55/−3
• LICENSE +1/−1
• README +9/−0
• spawn.cabal +24/−3

@@ -1,3 +1,5 @@+{-# LANGUAGE+    CPP #-} module Control.Concurrent.Spawn   ( -- * Spawn      spawn@@ -5,12 +7,18 @@     -- * Spawn with @'try'@   , Result   , spawnTry-  ++    -- * Higher-level functions+  , parMapIO+  , parMapIO_+  , (|*|)+     -- * Limiting concurrency   , pool ) where  import Control.Concurrent import Control.Exception+import Control.Monad  -- | Two ways a computation of type @'IO' a@ can end. type Result a = Either SomeException a@@ -18,14 +26,29 @@ -- | Spawn a concurrent computation.  Produces an action which -- demands a @'Result'@. spawnTry :: IO a -> IO (IO (Result a))++-- We block asynchronous exceptions around 'forkIO', then restore+-- the parent thread's exception mask state inside 'try'. This+-- prevents an exception from interrupting 'putMVar', which would+-- deadlock the parent.+--+-- The API for doing this changed in base-4.3 with GHC 7.0.++#if MIN_VERSION_base(4,3,0) spawnTry m = do   v <- newEmptyMVar-  -- block async exns, then unblock inside 'try' unless parent was blocked-  -- avoids dropping an exception+  _ <- mask $ \restore -> forkIO (try (restore m) >>= putMVar v)+  return (readMVar v)++#else+spawnTry m = do+  v <- newEmptyMVar   b <- blocked   _ <- block $ forkIO (try (if b then m else unblock m) >>= putMVar v)   return (readMVar v) +#endif+ -- | Spawn a concurrent computation.  Produces an action which -- demands the result.  Any exception from the original computation -- is re-thrown when and where the result is demanded.@@ -34,6 +57,7 @@   r <- spawnTry m   return (r >>= either throwIO return) + -- | Given /n/, produces a function to wrap @'IO'@ actions. -- No more than /n/ wrapped actions will be in progress at -- one time.@@ -41,3 +65,31 @@ pool n = do   s <- newQSem n   return $ bracket_ (waitQSem s) (signalQSem s)+++-- | Execute a separate thread of IO for each element of a list, and+-- collect results.+--+-- The analogy to @parMap@ is misleading.  The concurrent execution+-- of these actions is non-deterministic and can affect results.+-- However, @'parMapIO'@ is expected to be most useful for actions+-- which do not interact.+parMapIO :: (a -> IO b) -> [a] -> IO [b]+parMapIO f xs = mapM (spawn . f) xs >>= sequence++-- | Execute a separate thread of IO for each element of a list.+--+-- Results are discarded, but the @'parMapIO_'@ action does not+-- complete until all threads have finished.+parMapIO_ :: (a -> IO b) -> [a] -> IO ()+parMapIO_ f xs = mapM (spawn . f) xs >>= sequence_+++infixl 4 |*|++-- | A concurrent version of @'ap'@ or @(\<*\>)@ for @'IO'@.+--+-- Spawns a thread for the right-hand action, while executing the+-- left-hand action in the current thread.+(|*|) :: IO (a -> b) -> IO a -> IO b+mf |*| mx = spawn mx >>= (mf `ap`)

@@ -1,4 +1,4 @@-Copyright (c) Keegan McAllister 2010+Copyright (c) Keegan McAllister 2010, 2011  All rights reserved. 

@@ -0,0 +1,9 @@+spawn is a tiny Haskell library for concurrent computations.++Documentation is hosted at http://hackage.haskell.org/package/spawn++To build the documentation yourself, run++  $ cabal configure && cabal haddock --hyperlink-source++This will produce HTML documentation under dist/doc/html/spawn.

@@ -1,19 +1,40 @@ name:                spawn-version:             0.2+version:             0.3 license:             BSD3 license-file:        LICENSE-synopsis:            Tiny library for joinable computations / threads with results.+synopsis:            Tiny library for concurrent computations category:            Concurrency, Concurrent, Control author:              Keegan McAllister <mcallister.keegan@gmail.com> maintainer:          Keegan McAllister <mcallister.keegan@gmail.com> build-type:          Simple-cabal-version:       >=1.2+cabal-version:       >=1.6 description:   Spawn a concurrent 'IO' computation and later demand its result.  Tiny API   and implementation.+  .+  New in version 0.3:+  .+    * Added functions @parMapIO@, @parMapIO_@, and @(|*|)@, which capture+      common use cases of @spawn@.+  .+    * Updated code to avoid using deprecated functions with @base-4.3@ and+      later (GHC 7.0 and later).  The old code is still used with older+      @base@ libraries.+  .+    * Added public GitHub repository. +extra-source-files:+  README+ library   exposed-modules:   Control.Concurrent.Spawn   ghc-options:       -Wall   build-depends:       base >= 3 && < 5++  other-extensions:+      CPP++source-repository head+    type:     git+    location: git://github.com/kmcallister/spawn.git