hspec-core 2.4.7 → 2.4.8

raw patch · 2 files changed

+877/−5 lines, 2 filesdep +stmdep −asyncPVP ok

version bump matches the API change (PVP)

Dependencies added: stm

Dependencies removed: async

API changes (from Hackage documentation)

Files

• hspec-core.cabal +7/−5
• vendor/Control/Concurrent/Async.hs +870/−0

@@ -1,11 +1,11 @@--- This file has been generated from package.yaml by hpack version 0.21.2.+-- This file has been generated from package.yaml by hpack version 0.25.0. -- -- see: https://github.com/sol/hpack ----- hash: 5f2f775ba57cc471e22084afddafbeffb0a467d1863b8df967e9a4ae08874d1b+-- hash: 8fe188c041ee9e718cde6c89c51a73813fd9b52b772533362134c232c80261f5  name:             hspec-core-version:          2.4.7+version:          2.4.8 license:          MIT license-file:     LICENSE copyright:        (c) 2011-2017 Simon Hengel,@@ -36,7 +36,6 @@     , QuickCheck >=2.5.1     , ansi-terminal >=0.5     , array-    , async >=2     , base >=4.5.0.0 && <5     , call-stack     , deepseq@@ -46,6 +45,7 @@     , quickcheck-io >=0.2.0     , random     , setenv+    , stm >=2.2     , tf-random     , time     , transformers >=0.2.2.0@@ -71,6 +71,7 @@       Test.Hspec.Core.Spec.Monad       Test.Hspec.Core.Timer       Test.Hspec.Core.Tree+      Control.Concurrent.Async       Data.Algorithm.Diff       Paths_hspec_core   default-language: Haskell2010@@ -89,7 +90,6 @@     , QuickCheck >=2.5.1     , ansi-terminal >=0.5     , array-    , async >=2     , base >=4.5.0.0 && <5     , call-stack     , deepseq@@ -102,6 +102,7 @@     , random     , setenv     , silently >=1.2.4+    , stm >=2.2     , temporary     , tf-random     , time@@ -127,6 +128,7 @@       Test.Hspec.Core.Timer       Test.Hspec.Core.Tree       Test.Hspec.Core.Util+      Control.Concurrent.Async       Data.Algorithm.Diff       All       Helper

@@ -0,0 +1,870 @@+{-# LANGUAGE CPP, MagicHash, UnboxedTuples, RankNTypes,+    ExistentialQuantification #-}+#if __GLASGOW_HASKELL__ >= 701+{-# LANGUAGE Trustworthy #-}+#endif+#if __GLASGOW_HASKELL__ < 710+{-# LANGUAGE DeriveDataTypeable #-}+#endif+{-# OPTIONS -Wall #-}++-----------------------------------------------------------------------------+-- |+-- Module      :  Control.Concurrent.Async+-- Copyright   :  (c) Simon Marlow 2012+-- License     :  BSD3 (see the file LICENSE)+--+-- Maintainer  :  Simon Marlow <marlowsd@gmail.com>+-- Stability   :  provisional+-- Portability :  non-portable (requires concurrency)+--+-- This module provides a set of operations for running IO operations+-- asynchronously and waiting for their results.  It is a thin layer+-- over the basic concurrency operations provided by+-- "Control.Concurrent".  The main additional functionality it+-- provides is the ability to wait for the return value of a thread,+-- but the interface also provides some additional safety and+-- robustness over using threads and @MVar@ directly.+--+-- The basic type is @'Async' a@, which represents an asynchronous+-- @IO@ action that will return a value of type @a@, or die with an+-- exception.  An @Async@ corresponds to a thread, and its 'ThreadId'+-- can be obtained with 'asyncThreadId', although that should rarely+-- be necessary.+--+-- For example, to fetch two web pages at the same time, we could do+-- this (assuming a suitable @getURL@ function):+--+-- >    do a1 <- async (getURL url1)+-- >       a2 <- async (getURL url2)+-- >       page1 <- wait a1+-- >       page2 <- wait a2+-- >       ...+--+-- where 'async' starts the operation in a separate thread, and+-- 'wait' waits for and returns the result.  If the operation+-- throws an exception, then that exception is re-thrown by+-- 'wait'.  This is one of the ways in which this library+-- provides some additional safety: it is harder to accidentally+-- forget about exceptions thrown in child threads.+--+-- A slight improvement over the previous example is this:+--+-- >       withAsync (getURL url1) $ \a1 -> do+-- >       withAsync (getURL url2) $ \a2 -> do+-- >       page1 <- wait a1+-- >       page2 <- wait a2+-- >       ...+--+-- 'withAsync' is like 'async', except that the 'Async' is+-- automatically killed (using 'uninterruptibleCancel') if the+-- enclosing IO operation returns before it has completed.  Consider+-- the case when the first 'wait' throws an exception; then the second+-- 'Async' will be automatically killed rather than being left to run+-- in the background, possibly indefinitely.  This is the second way+-- that the library provides additional safety: using 'withAsync'+-- means we can avoid accidentally leaving threads running.+-- Furthermore, 'withAsync' allows a tree of threads to be built, such+-- that children are automatically killed if their parents die for any+-- reason.+--+-- The pattern of performing two IO actions concurrently and waiting+-- for their results is packaged up in a combinator 'concurrently', so+-- we can further shorten the above example to:+--+-- >       (page1, page2) <- concurrently (getURL url1) (getURL url2)+-- >       ...+--+-- The 'Functor' instance can be used to change the result of an+-- 'Async'.  For example:+--+-- > ghci> a <- async (return 3)+-- > ghci> wait a+-- > 3+-- > ghci> wait (fmap (+1) a)+-- > 4++-----------------------------------------------------------------------------++module Control.Concurrent.Async (++    -- * Asynchronous actions+    Async,+    -- ** Spawning+    async, asyncBound, asyncOn, asyncWithUnmask, asyncOnWithUnmask,++    -- ** Spawning with automatic 'cancel'ation+    withAsync, withAsyncBound, withAsyncOn, withAsyncWithUnmask,+    withAsyncOnWithUnmask,++    -- ** Querying 'Async's+    wait, poll, waitCatch, asyncThreadId,+    cancel, uninterruptibleCancel, cancelWith, AsyncCancelled(..),++    -- ** STM operations+    waitSTM, pollSTM, waitCatchSTM,++    -- ** Waiting for multiple 'Async's+    waitAny, waitAnyCatch, waitAnyCancel, waitAnyCatchCancel,+    waitEither, waitEitherCatch, waitEitherCancel, waitEitherCatchCancel,+    waitEither_,+    waitBoth,++    -- ** Waiting for multiple 'Async's in STM+    waitAnySTM, waitAnyCatchSTM,+    waitEitherSTM, waitEitherCatchSTM,+    waitEitherSTM_,+    waitBothSTM,++    -- ** Linking+    link, link2, ExceptionInLinkedThread(..),++    -- * Convenient utilities+    race, race_,+    concurrently, concurrently_,+    mapConcurrently, forConcurrently,+    mapConcurrently_, forConcurrently_,+    replicateConcurrently, replicateConcurrently_,+    Concurrently(..),+    compareAsyncs,++  ) where++import Control.Concurrent.STM+import Control.Exception+import Control.Concurrent+import qualified Data.Foldable as F+#if !MIN_VERSION_base(4,6,0)+import Prelude hiding (catch)+#endif+import Control.Monad+import Control.Applicative+#if !MIN_VERSION_base(4,8,0)+import Data.Monoid (Monoid(mempty,mappend))+import Data.Traversable+#endif+#if __GLASGOW_HASKELL__ < 710+import Data.Typeable+#endif+#if MIN_VERSION_base(4,9,0)+import Data.Semigroup (Semigroup((<>)))+#endif++import Data.IORef++import GHC.Exts+import GHC.IO hiding (finally, onException)+import GHC.Conc++-- -----------------------------------------------------------------------------+-- STM Async API+++-- | An asynchronous action spawned by 'async' or 'withAsync'.+-- Asynchronous actions are executed in a separate thread, and+-- operations are provided for waiting for asynchronous actions to+-- complete and obtaining their results (see e.g. 'wait').+--+data Async a = Async+  { asyncThreadId :: {-# UNPACK #-} !ThreadId+                  -- ^ Returns the 'ThreadId' of the thread running+                  -- the given 'Async'.+  , _asyncWait    :: STM (Either SomeException a)+  }++instance Eq (Async a) where+  Async a _ == Async b _  =  a == b++instance Ord (Async a) where+  Async a _ `compare` Async b _  =  a `compare` b++instance Functor Async where+  fmap f (Async a w) = Async a (fmap (fmap f) w)++-- | Compare two 'Async's that may have different types+compareAsyncs :: Async a -> Async b -> Ordering+compareAsyncs (Async t1 _) (Async t2 _) = compare t1 t2++-- | Spawn an asynchronous action in a separate thread.+async :: IO a -> IO (Async a)+async = inline asyncUsing rawForkIO++-- | Like 'async' but using 'forkOS' internally.+asyncBound :: IO a -> IO (Async a)+asyncBound = asyncUsing forkOS++-- | Like 'async' but using 'forkOn' internally.+asyncOn :: Int -> IO a -> IO (Async a)+asyncOn = asyncUsing . rawForkOn++-- | Like 'async' but using 'forkIOWithUnmask' internally.  The child+-- thread is passed a function that can be used to unmask asynchronous+-- exceptions.+asyncWithUnmask :: ((forall b . IO b -> IO b) -> IO a) -> IO (Async a)+asyncWithUnmask actionWith = asyncUsing rawForkIO (actionWith unsafeUnmask)++-- | Like 'asyncOn' but using 'forkOnWithUnmask' internally.  The+-- child thread is passed a function that can be used to unmask+-- asynchronous exceptions.+asyncOnWithUnmask :: Int -> ((forall b . IO b -> IO b) -> IO a) -> IO (Async a)+asyncOnWithUnmask cpu actionWith =+  asyncUsing (rawForkOn cpu) (actionWith unsafeUnmask)++asyncUsing :: (IO () -> IO ThreadId)+           -> IO a -> IO (Async a)+asyncUsing doFork = \action -> do+   var <- newEmptyTMVarIO+   -- t <- forkFinally action (\r -> atomically $ putTMVar var r)+   -- slightly faster:+   t <- mask $ \restore ->+          doFork $ try (restore action) >>= atomically . putTMVar var+   return (Async t (readTMVar var))++-- | Spawn an asynchronous action in a separate thread, and pass its+-- @Async@ handle to the supplied function.  When the function returns+-- or throws an exception, 'uninterruptibleCancel' is called on the @Async@.+--+-- > withAsync action inner = mask $ \restore -> do+-- >   a <- async (restore action)+-- >   restore inner `finally` uninterruptibleCancel a+--+-- This is a useful variant of 'async' that ensures an @Async@ is+-- never left running unintentionally.+--+-- Note: a reference to the child thread is kept alive until the call+-- to `withAsync` returns, so nesting many `withAsync` calls requires+-- linear memory.+--+withAsync :: IO a -> (Async a -> IO b) -> IO b+withAsync = inline withAsyncUsing rawForkIO++-- | Like 'withAsync' but uses 'forkOS' internally.+withAsyncBound :: IO a -> (Async a -> IO b) -> IO b+withAsyncBound = withAsyncUsing forkOS++-- | Like 'withAsync' but uses 'forkOn' internally.+withAsyncOn :: Int -> IO a -> (Async a -> IO b) -> IO b+withAsyncOn = withAsyncUsing . rawForkOn++-- | Like 'withAsync' but uses 'forkIOWithUnmask' internally.  The+-- child thread is passed a function that can be used to unmask+-- asynchronous exceptions.+withAsyncWithUnmask+  :: ((forall c. IO c -> IO c) -> IO a) -> (Async a -> IO b) -> IO b+withAsyncWithUnmask actionWith =+  withAsyncUsing rawForkIO (actionWith unsafeUnmask)++-- | Like 'withAsyncOn' but uses 'forkOnWithUnmask' internally.  The+-- child thread is passed a function that can be used to unmask+-- asynchronous exceptions+withAsyncOnWithUnmask+  :: Int -> ((forall c. IO c -> IO c) -> IO a) -> (Async a -> IO b) -> IO b+withAsyncOnWithUnmask cpu actionWith =+  withAsyncUsing (rawForkOn cpu) (actionWith unsafeUnmask)++withAsyncUsing :: (IO () -> IO ThreadId)+               -> IO a -> (Async a -> IO b) -> IO b+-- The bracket version works, but is slow.  We can do better by+-- hand-coding it:+withAsyncUsing doFork = \action inner -> do+  var <- newEmptyTMVarIO+  mask $ \restore -> do+    t <- doFork $ try (restore action) >>= atomically . putTMVar var+    let a = Async t (readTMVar var)+    r <- restore (inner a) `catchAll` \e -> do+      uninterruptibleCancel a+      throwIO e+    uninterruptibleCancel a+    return r++-- | Wait for an asynchronous action to complete, and return its+-- value.  If the asynchronous action threw an exception, then the+-- exception is re-thrown by 'wait'.+--+-- > wait = atomically . waitSTM+--+{-# INLINE wait #-}+wait :: Async a -> IO a+wait = atomically . waitSTM++-- | Wait for an asynchronous action to complete, and return either+-- @Left e@ if the action raised an exception @e@, or @Right a@ if it+-- returned a value @a@.+--+-- > waitCatch = atomically . waitCatchSTM+--+{-# INLINE waitCatch #-}+waitCatch :: Async a -> IO (Either SomeException a)+waitCatch = tryAgain . atomically . waitCatchSTM+  where+    -- See: https://github.com/simonmar/async/issues/14+    tryAgain f = f `catch` \BlockedIndefinitelyOnSTM -> f++-- | Check whether an 'Async' has completed yet.  If it has not+-- completed yet, then the result is @Nothing@, otherwise the result+-- is @Just e@ where @e@ is @Left x@ if the @Async@ raised an+-- exception @x@, or @Right a@ if it returned a value @a@.+--+-- > poll = atomically . pollSTM+--+{-# INLINE poll #-}+poll :: Async a -> IO (Maybe (Either SomeException a))+poll = atomically . pollSTM++-- | A version of 'wait' that can be used inside an STM transaction.+--+waitSTM :: Async a -> STM a+waitSTM a = do+   r <- waitCatchSTM a+   either throwSTM return r++-- | A version of 'waitCatch' that can be used inside an STM transaction.+--+{-# INLINE waitCatchSTM #-}+waitCatchSTM :: Async a -> STM (Either SomeException a)+waitCatchSTM (Async _ w) = w++-- | A version of 'poll' that can be used inside an STM transaction.+--+{-# INLINE pollSTM #-}+pollSTM :: Async a -> STM (Maybe (Either SomeException a))+pollSTM (Async _ w) = (Just <$> w) `orElse` return Nothing++-- | Cancel an asynchronous action by throwing the @AsyncCancelled@+-- exception to it, and waiting for the `Async` thread to quit.+-- Has no effect if the 'Async' has already completed.+--+-- > cancel a = throwTo (asyncThreadId a) AsyncCancelled <* waitCatch a+--+-- Note that 'cancel' will not terminate until the thread the 'Async'+-- refers to has terminated. This means that 'cancel' will block for+-- as long said thread blocks when receiving an asynchronous exception.+--+-- For example, it could block if:+--+-- * It's executing a foreign call, and thus cannot receive the asynchronous+-- exception;+-- * It's executing some cleanup handler after having received the exception,+-- and the handler is blocking.+{-# INLINE cancel #-}+cancel :: Async a -> IO ()+cancel a@(Async t _) = throwTo t AsyncCancelled <* waitCatch a++-- | The exception thrown by `cancel` to terminate a thread.+data AsyncCancelled = AsyncCancelled+  deriving (Show, Eq+#if __GLASGOW_HASKELL__ < 710+    ,Typeable+#endif+    )++instance Exception AsyncCancelled where+#if __GLASGOW_HASKELL__ >= 708+  fromException = asyncExceptionFromException+  toException = asyncExceptionToException+#endif++-- | Cancel an asynchronous action+--+-- This is a variant of `cancel`, but it is not interruptible.+{-# INLINE uninterruptibleCancel #-}+uninterruptibleCancel :: Async a -> IO ()+uninterruptibleCancel = uninterruptibleMask_ . cancel++-- | Cancel an asynchronous action by throwing the supplied exception+-- to it.+--+-- > cancelWith a x = throwTo (asyncThreadId a) x+--+-- The notes about the synchronous nature of 'cancel' also apply to+-- 'cancelWith'.+cancelWith :: Exception e => Async a -> e -> IO ()+cancelWith a@(Async t _) e = throwTo t e <* waitCatch a++-- | Wait for any of the supplied asynchronous operations to complete.+-- The value returned is a pair of the 'Async' that completed, and the+-- result that would be returned by 'wait' on that 'Async'.+--+-- If multiple 'Async's complete or have completed, then the value+-- returned corresponds to the first completed 'Async' in the list.+--+{-# INLINE waitAnyCatch #-}+waitAnyCatch :: [Async a] -> IO (Async a, Either SomeException a)+waitAnyCatch = atomically . waitAnyCatchSTM++-- | A version of 'waitAnyCatch' that can be used inside an STM transaction.+--+-- @since 2.1.0+waitAnyCatchSTM :: [Async a] -> STM (Async a, Either SomeException a)+waitAnyCatchSTM asyncs =+    foldr orElse retry $+      map (\a -> do r <- waitCatchSTM a; return (a, r)) asyncs++-- | Like 'waitAnyCatch', but also cancels the other asynchronous+-- operations as soon as one has completed.+--+waitAnyCatchCancel :: [Async a] -> IO (Async a, Either SomeException a)+waitAnyCatchCancel asyncs =+  waitAnyCatch asyncs `finally` mapM_ cancel asyncs++-- | Wait for any of the supplied @Async@s to complete.  If the first+-- to complete throws an exception, then that exception is re-thrown+-- by 'waitAny'.+--+-- If multiple 'Async's complete or have completed, then the value+-- returned corresponds to the first completed 'Async' in the list.+--+{-# INLINE waitAny #-}+waitAny :: [Async a] -> IO (Async a, a)+waitAny = atomically . waitAnySTM++-- | A version of 'waitAny' that can be used inside an STM transaction.+--+-- @since 2.1.0+waitAnySTM :: [Async a] -> STM (Async a, a)+waitAnySTM asyncs =+    foldr orElse retry $+      map (\a -> do r <- waitSTM a; return (a, r)) asyncs++-- | Like 'waitAny', but also cancels the other asynchronous+-- operations as soon as one has completed.+--+waitAnyCancel :: [Async a] -> IO (Async a, a)+waitAnyCancel asyncs =+  waitAny asyncs `finally` mapM_ cancel asyncs++-- | Wait for the first of two @Async@s to finish.+{-# INLINE waitEitherCatch #-}+waitEitherCatch :: Async a -> Async b+                -> IO (Either (Either SomeException a)+                              (Either SomeException b))+waitEitherCatch left right =+  tryAgain $ atomically (waitEitherCatchSTM left right)+  where+    -- See: https://github.com/simonmar/async/issues/14+    tryAgain f = f `catch` \BlockedIndefinitelyOnSTM -> f++-- | A version of 'waitEitherCatch' that can be used inside an STM transaction.+--+-- @since 2.1.0+waitEitherCatchSTM :: Async a -> Async b+                -> STM (Either (Either SomeException a)+                               (Either SomeException b))+waitEitherCatchSTM left right =+    (Left  <$> waitCatchSTM left)+      `orElse`+    (Right <$> waitCatchSTM right)++-- | Like 'waitEitherCatch', but also 'cancel's both @Async@s before+-- returning.+--+waitEitherCatchCancel :: Async a -> Async b+                      -> IO (Either (Either SomeException a)+                                    (Either SomeException b))+waitEitherCatchCancel left right =+  waitEitherCatch left right `finally` (cancel left >> cancel right)++-- | Wait for the first of two @Async@s to finish.  If the @Async@+-- that finished first raised an exception, then the exception is+-- re-thrown by 'waitEither'.+--+{-# INLINE waitEither #-}+waitEither :: Async a -> Async b -> IO (Either a b)+waitEither left right = atomically (waitEitherSTM left right)++-- | A version of 'waitEither' that can be used inside an STM transaction.+--+-- @since 2.1.0+waitEitherSTM :: Async a -> Async b -> STM (Either a b)+waitEitherSTM left right =+    (Left  <$> waitSTM left)+      `orElse`+    (Right <$> waitSTM right)++-- | Like 'waitEither', but the result is ignored.+--+{-# INLINE waitEither_ #-}+waitEither_ :: Async a -> Async b -> IO ()+waitEither_ left right = atomically (waitEitherSTM_ left right)++-- | A version of 'waitEither_' that can be used inside an STM transaction.+--+-- @since 2.1.0+waitEitherSTM_:: Async a -> Async b -> STM ()+waitEitherSTM_ left right =+    (void $ waitSTM left)+      `orElse`+    (void $ waitSTM right)++-- | Like 'waitEither', but also 'cancel's both @Async@s before+-- returning.+--+waitEitherCancel :: Async a -> Async b -> IO (Either a b)+waitEitherCancel left right =+  waitEither left right `finally` (cancel left >> cancel right)++-- | Waits for both @Async@s to finish, but if either of them throws+-- an exception before they have both finished, then the exception is+-- re-thrown by 'waitBoth'.+--+{-# INLINE waitBoth #-}+waitBoth :: Async a -> Async b -> IO (a,b)+waitBoth left right = atomically (waitBothSTM left right)++-- | A version of 'waitBoth' that can be used inside an STM transaction.+--+-- @since 2.1.0+waitBothSTM :: Async a -> Async b -> STM (a,b)+waitBothSTM left right = do+    a <- waitSTM left+           `orElse`+         (waitSTM right >> retry)+    b <- waitSTM right+    return (a,b)+++-- -----------------------------------------------------------------------------+-- Linking threads++data ExceptionInLinkedThread =+  forall a . ExceptionInLinkedThread (Async a) SomeException+#if __GLASGOW_HASKELL__ < 710+  deriving Typeable+#endif++instance Show ExceptionInLinkedThread where+  show (ExceptionInLinkedThread (Async t _) e) =+    "ExceptionInLinkedThread " ++ show t ++ " " ++ show e++instance Exception ExceptionInLinkedThread where+#if __GLASGOW_HASKELL__ >= 708+  fromException = asyncExceptionFromException+  toException = asyncExceptionToException+#endif++-- | Link the given @Async@ to the current thread, such that if the+-- @Async@ raises an exception, that exception will be re-thrown in+-- the current thread, wrapped in 'ExceptionInLinkedThread'.+--+-- 'link' ignores 'AsyncCancelled' exceptions thrown in the other thread,+-- so that it's safe to 'cancel' a thread you're linked to.  If you want+-- different behaviour, use 'linkOnly'.+--+link :: Async a -> IO ()+link = linkOnly (not . isCancel)++-- | Link the given @Async@ to the current thread, such that if the+-- @Async@ raises an exception, that exception will be re-thrown in+-- the current thread.  The supplied predicate determines which+-- exceptions in the target thread should be propagated to the source+-- thread.+--+linkOnly+  :: (SomeException -> Bool)  -- ^ return 'True' if the exception+                              -- should be propagated, 'False'+                              -- otherwise.+  -> Async a+  -> IO ()+linkOnly shouldThrow a = do+  me <- myThreadId+  void $ forkRepeat $ do+    r <- waitCatch a+    case r of+      Left e | shouldThrow e -> throwTo me (ExceptionInLinkedThread a e)+      _otherwise -> return ()++-- | Link two @Async@s together, such that if either raises an+-- exception, the same exception is re-thrown in the other @Async@,+-- wrapped in 'ExceptionInLinkedThread'.+--+-- 'link2' ignores 'AsyncCancelled' exceptions, so that it's possible+-- to 'cancel' either thread without cancelling the other.  If you+-- want different behaviour, use 'link2Only'.+--+link2 :: Async a -> Async b -> IO ()+link2 = link2Only (not . isCancel)++link2Only :: (SomeException -> Bool) -> Async a -> Async b -> IO ()+link2Only shouldThrow left@(Async tl _)  right@(Async tr _) =+  void $ forkRepeat $ do+    r <- waitEitherCatch left right+    case r of+      Left  (Left e) | shouldThrow e ->+        throwTo tr (ExceptionInLinkedThread left e)+      Right (Left e) | shouldThrow e ->+        throwTo tl (ExceptionInLinkedThread right e)+      _ -> return ()++isCancel :: SomeException -> Bool+isCancel e+  | Just AsyncCancelled <- fromException e = True+  | otherwise = False+++-- -----------------------------------------------------------------------------++-- | Run two @IO@ actions concurrently, and return the first to+-- finish.  The loser of the race is 'cancel'led.+--+-- > race left right =+-- >   withAsync left $ \a ->+-- >   withAsync right $ \b ->+-- >   waitEither a b+--+race :: IO a -> IO b -> IO (Either a b)++-- | Like 'race', but the result is ignored.+--+race_ :: IO a -> IO b -> IO ()++-- | Run two @IO@ actions concurrently, and return both results.  If+-- either action throws an exception at any time, then the other+-- action is 'cancel'led, and the exception is re-thrown by+-- 'concurrently'.+--+-- > concurrently left right =+-- >   withAsync left $ \a ->+-- >   withAsync right $ \b ->+-- >   waitBoth a b+concurrently :: IO a -> IO b -> IO (a,b)++#define USE_ASYNC_VERSIONS 0++#if USE_ASYNC_VERSIONS++race left right =+  withAsync left $ \a ->+  withAsync right $ \b ->+  waitEither a b++race_ left right =+  withAsync left $ \a ->+  withAsync right $ \b ->+  waitEither_ a b++concurrently left right =+  withAsync left $ \a ->+  withAsync right $ \b ->+  waitBoth a b++#else++-- MVar versions of race/concurrently+-- More ugly than the Async versions, but quite a bit faster.++-- race :: IO a -> IO b -> IO (Either a b)+race left right = concurrently' left right collect+  where+    collect m = do+        e <- m+        case e of+            Left ex -> throwIO ex+            Right r -> return r++-- race_ :: IO a -> IO b -> IO ()+race_ left right = void $ race left right++-- concurrently :: IO a -> IO b -> IO (a,b)+concurrently left right = concurrently' left right (collect [])+  where+    collect [Left a, Right b] _ = return (a,b)+    collect [Right b, Left a] _ = return (a,b)+    collect xs m = do+        e <- m+        case e of+            Left ex -> throwIO ex+            Right r -> collect (r:xs) m++concurrently' :: IO a -> IO b+             -> (IO (Either SomeException (Either a b)) -> IO r)+             -> IO r+concurrently' left right collect = do+    done <- newEmptyMVar+    mask $ \restore -> do+        -- Note: uninterruptibleMask here is because we must not allow+        -- the putMVar in the exception handler to be interrupted,+        -- otherwise the parent thread will deadlock when it waits for+        -- the thread to terminate.+        lid <- forkIO $ uninterruptibleMask_ $+          restore (left >>= putMVar done . Right . Left)+            `catchAll` (putMVar done . Left)+        rid <- forkIO $ uninterruptibleMask_ $+          restore (right >>= putMVar done . Right . Right)+            `catchAll` (putMVar done . Left)++        count <- newIORef (2 :: Int)+        let takeDone = do+                r <- takeMVar done      -- interruptible+                -- Decrement the counter so we know how many takes are left.+                -- Since only the parent thread is calling this, we can+                -- use non-atomic modifications.+                -- NB. do this *after* takeMVar, because takeMVar might be+                -- interrupted.+                modifyIORef count (subtract 1)+                return r++        let tryAgain f = f `catch` \BlockedIndefinitelyOnMVar -> f++            stop = do+                -- kill right before left, to match the semantics of+                -- the version using withAsync. (#27)+                uninterruptibleMask_ $ do+                  count' <- readIORef count+                  -- we only need to use killThread if there are still+                  -- children alive.  Note: forkIO here is because the+                  -- child thread could be in an uninterruptible+                  -- putMVar.+                  when (count' > 0) $+                    void $ forkIO $ do+                      throwTo rid AsyncCancelled+                      throwTo lid AsyncCancelled+                  -- ensure the children are really dead+                  replicateM_ count' (tryAgain $ takeMVar done)++        r <- collect (tryAgain $ takeDone) `onException` stop+        stop+        return r++#endif++-- | maps an @IO@-performing function over any @Traversable@ data+-- type, performing all the @IO@ actions concurrently, and returning+-- the original data structure with the arguments replaced by the+-- results.+--+-- If any of the actions throw an exception, then all other actions are+-- cancelled and the exception is re-thrown.+--+-- For example, @mapConcurrently@ works with lists:+--+-- > pages <- mapConcurrently getURL ["url1", "url2", "url3"]+--+mapConcurrently :: Traversable t => (a -> IO b) -> t a -> IO (t b)+mapConcurrently f = runConcurrently . traverse (Concurrently . f)++-- | `forConcurrently` is `mapConcurrently` with its arguments flipped+--+-- > pages <- forConcurrently ["url1", "url2", "url3"] $ \url -> getURL url+--+-- @since 2.1.0+forConcurrently :: Traversable t => t a -> (a -> IO b) -> IO (t b)+forConcurrently = flip mapConcurrently++-- | `mapConcurrently_` is `mapConcurrently` with the return value discarded,+-- just like @mapM_+mapConcurrently_ :: F.Foldable f => (a -> IO b) -> f a -> IO ()+mapConcurrently_ f = runConcurrently . F.foldMap (Concurrently . void . f)++-- | `forConcurrently_` is `forConcurrently` with the return value discarded,+-- just like @forM_+forConcurrently_ :: F.Foldable f => f a -> (a -> IO b) -> IO ()+forConcurrently_ = flip mapConcurrently_++-- | 'concurrently', but ignore the result values+--+-- @since 2.1.1+concurrently_ :: IO a -> IO b -> IO ()+concurrently_ left right = concurrently' left right (collect 0)+  where+    collect 2 _ = return ()+    collect i m = do+        e <- m+        case e of+            Left ex -> throwIO ex+            Right _ -> collect (i + 1 :: Int) m++-- | Perform the action in the given number of threads.+--+-- @since 2.1.1+replicateConcurrently :: Int -> IO a -> IO [a]+replicateConcurrently cnt = runConcurrently . sequenceA . replicate cnt . Concurrently++-- | Same as 'replicateConcurrently', but ignore the results.+--+-- @since 2.1.1+replicateConcurrently_ :: Int -> IO a -> IO ()+replicateConcurrently_ cnt = runConcurrently . F.fold . replicate cnt . Concurrently . void++-- -----------------------------------------------------------------------------++-- | A value of type @Concurrently a@ is an @IO@ operation that can be+-- composed with other @Concurrently@ values, using the @Applicative@+-- and @Alternative@ instances.+--+-- Calling @runConcurrently@ on a value of type @Concurrently a@ will+-- execute the @IO@ operations it contains concurrently, before+-- delivering the result of type @a@.+--+-- For example+--+-- > (page1, page2, page3)+-- >     <- runConcurrently $ (,,)+-- >     <$> Concurrently (getURL "url1")+-- >     <*> Concurrently (getURL "url2")+-- >     <*> Concurrently (getURL "url3")+--+newtype Concurrently a = Concurrently { runConcurrently :: IO a }++instance Functor Concurrently where+  fmap f (Concurrently a) = Concurrently $ f <$> a++instance Applicative Concurrently where+  pure = Concurrently . return+  Concurrently fs <*> Concurrently as =+    Concurrently $ (\(f, a) -> f a) <$> concurrently fs as++instance Alternative Concurrently where+  empty = Concurrently $ forever (threadDelay maxBound)+  Concurrently as <|> Concurrently bs =+    Concurrently $ either id id <$> race as bs++#if MIN_VERSION_base(4,9,0)+-- | Only defined by @async@ for @base >= 4.9@+--+-- @since 2.1.0+instance Semigroup a => Semigroup (Concurrently a) where+  (<>) = liftA2 (<>)++-- | @since 2.1.0+instance (Semigroup a, Monoid a) => Monoid (Concurrently a) where+  mempty = pure mempty+  mappend = (<>)+#else+-- | @since 2.1.0+instance Monoid a => Monoid (Concurrently a) where+  mempty = pure mempty+  mappend = liftA2 mappend+#endif++-- ----------------------------------------------------------------------------++-- | Fork a thread that runs the supplied action, and if it raises an+-- exception, re-runs the action.  The thread terminates only when the+-- action runs to completion without raising an exception.+forkRepeat :: IO a -> IO ThreadId+forkRepeat action =+  mask $ \restore ->+    let go = do r <- tryAll (restore action)+                case r of+                  Left _ -> go+                  _      -> return ()+    in forkIO go++catchAll :: IO a -> (SomeException -> IO a) -> IO a+catchAll = catch++tryAll :: IO a -> IO (Either SomeException a)+tryAll = try++-- A version of forkIO that does not include the outer exception+-- handler: saves a bit of time when we will be installing our own+-- exception handler.+{-# INLINE rawForkIO #-}+rawForkIO :: IO () -> IO ThreadId+rawForkIO action = IO $ \ s ->+   case (fork# action s) of (# s1, tid #) -> (# s1, ThreadId tid #)++{-# INLINE rawForkOn #-}+rawForkOn :: Int -> IO () -> IO ThreadId+rawForkOn (I# cpu) action = IO $ \ s ->+   case (forkOn# cpu action s) of (# s1, tid #) -> (# s1, ThreadId tid #)