distributed-fork (empty) → 0.0.1.0

raw patch · 8 files changed

+1181/−0 lines, 8 filesdep +asyncdep +basedep +binary

Dependencies added: async, base, binary, bytestring, constraints, distributed-closure, distributed-fork, exceptions, stm, tasty, tasty-hunit, terminal-size, text, transformers, typed-process, unix

Files

• LICENSE +674/−0
• distributed-fork.cabal +53/−0
• src/Control/Distributed/Fork.hs +88/−0
• src/Control/Distributed/Fork/Backend.hs +56/−0
• src/Control/Distributed/Fork/Internal.hs +163/−0
• src/Control/Distributed/Fork/LocalProcessBackend.hs +18/−0
• src/Control/Distributed/Fork/Utils.hs +82/−0
• test/Test.hs +47/−0

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If not, see <http://www.gnu.org/licenses/>.++Also add information on how to contact you by electronic and paper mail.++  If the program does terminal interaction, make it output a short+notice like this when it starts in an interactive mode:++    <program>  Copyright (C) <year>  <name of author>+    This program comes with ABSOLUTELY NO WARRANTY; for details type `show w'.+    This is free software, and you are welcome to redistribute it+    under certain conditions; type `show c' for details.++The hypothetical commands `show w' and `show c' should show the appropriate+parts of the General Public License.  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@@ -0,0 +1,53 @@+name:                distributed-fork+version:             0.0.1.0+synopsis:            Like 'forkIO', but uses remote machines instead of local threads.+homepage:            https://github.com/utdemir/distributed-fork+license:             BSD3+license-file:        LICENSE+author:              Utku Demir+maintainer:          me@utdemir.com+copyright:           Utku Demir+category:            Control+build-type:          Simple+cabal-version:       >=1.10++description:+    This library provides a way to offload a computation to another machine.+    .+    It uses pluggable 'Backend''s to spawn remote executors. It currently only supports AWS Lambda using <http://hackage.haskell.org/package/distributed-fork-aws-lambda distributed-fork-aws-lambda> library.+    .+    See <https://github.com/utdemir/distributed-fork README> for the rationale behind the library and "Control.Distributed.Fork" module for the usage.++library+  hs-source-dirs:      src+  default-language:    Haskell2010+  exposed-modules:     Control.Distributed.Fork+                     , Control.Distributed.Fork.Utils+                     , Control.Distributed.Fork.LocalProcessBackend+                     , Control.Distributed.Fork.Backend+  other-modules:       Control.Distributed.Fork.Internal+  ghc-options:         -Wall+  build-depends:       base >= 4.7 && < 5+                     , async+                     , binary+                     , bytestring+                     , constraints+                     , distributed-closure+                     , exceptions+                     , stm+                     , text+                     , terminal-size+                     , transformers+                     , typed-process++test-suite tests+  type:             exitcode-stdio-1.0+  hs-source-dirs:   test+  main-is:          Test.hs+  default-language: Haskell2010+  ghc-options:      -Wall -threaded+  build-depends:    base >=4.7 && < 5+                  , distributed-fork+                  , tasty+                  , tasty-hunit+                  , unix

@@ -0,0 +1,88 @@+-- |+-- This module provides a common interface for offloading an IO action to remote executors.+--+-- It uses+-- <https://downloads.haskell.org/~ghc/latest/docs/html/users_guide/glasgow_exts.html#static-pointers StaticPointers language extension> and+-- <https://hackage.haskell.org/package/distributed-closure distributed-closure> library+-- for serializing closures to run remotely.+-- <https://ocharles.org.uk/blog/guest-posts/2014-12-23-static-pointers.html This blog post>+-- is a good introduction for those.+--+-- In short, if you you need a @'Closure' a@:+--+--     * If @a@ is statically known (eg. a top level value, or if it does not+--   depend on anything on the scope), use @static@ keyword coming from+--   @StaticPointers@ extension.+--+--     * If @a@ is a runtime value, use 'cpure' to lift it to @Closure a@. It will ask+--   for a @('Closure' ('Dict' ('Serializable' a)))@. If there is @('Binary' a)@ and+--   @('Typeable' a)@ instances, you can just use @(static 'Dict')@ for that.+--+-- One important constraint when using this library is that it assumes the remote+-- environment is capable of executing the exact same binary. On most cases, this+-- requires your host environment to be Linux. In future I plan to provide a set+-- of scripts using Docker to overcome this limitation.+module Control.Distributed.Fork+  ( fork+  , await+  , initDistributedFork+  , Backend+  , Handle++  , ExecutorStatus (..)+  , ExecutorPendingStatus (..)+  , ExecutorFinalStatus (..)++  -- * Exceptions+  , ExecutorFailedException (..)++  -- * Re-exports+  , Serializable+  , Closure+  , cap+  , cpure+  , Dict (Dict)+  ) where++--------------------------------------------------------------------------------+import           Control.Distributed.Closure+import           Control.Monad+import           Control.Monad.Catch+import           Data.Text                         (Text)+--------------------------------------------------------------------------------+import           Control.Distributed.Fork.Internal+--------------------------------------------------------------------------------++-- |+-- Asynchronously executes the given function using the 'Backend' and returns+-- an 'Handle'.+--+-- @+-- {-\# LANGUAGE StaticPointers #-}+--+-- import Control.Distributed.Fork+-- import Control.Distributed.Fork.LocalProcessBackend+--+-- main :: IO ()+-- main = do+--   'initDistributedFork'+--   handle <- 'fork' 'localProcessBackend' (static 'Dict') (static (return "Hello World!"))+--   putStrLn =<< await handle+fork :: Backend+     -> Closure (Dict (Serializable a))+     -> Closure (IO a)+     -> IO (Handle a)+fork b d c = runBackend d c b++-- |+-- Blocks until the 'Handle' completes.+--+-- Can throw 'ExecutorFailedException'.+await :: Handle a -> IO a+await = tryAwait >=> either (throwM . ExecutorFailedException) return++--------------------------------------------------------------------------------++newtype ExecutorFailedException = ExecutorFailedException Text+  deriving (Show, Eq)+instance Exception ExecutorFailedException

@@ -0,0 +1,56 @@+{-|+You only need this module if you want to create a new backend for distributed-fork.++See 'Control.Distributed.Fork.LocalProcessBackend' for a minimal example.+-}++module Control.Distributed.Fork.Backend+  (+    -- * Writing a 'Backend'.+    Backend (..)+  , BackendM+  , argExecutorMode++    -- * Reporting status+  , ExecutorFinalStatus (..)+  , ExecutorStatus(..)+  , ExecutorPendingStatus (..)+  , waiting, waitingDesc+  , submitted, submittedDesc+  , started, startedDesc+++  -- * Re-exports+  , liftIO+  , getExecutablePath+  ) where++--------------------------------------------------------------------------------+import           Control.Monad.IO.Class+import           Control.Monad.Trans.Reader+import           Data.Text                           (Text)+import           System.Environment+--------------------------------------------------------------------------------+import           Control.Distributed.Fork.Internal+--------------------------------------------------------------------------------++pendingStatus :: ExecutorPendingStatus -> BackendM ()+pendingStatus s = BackendM ask >>= liftIO . ($ s)++waiting :: BackendM ()+waiting = pendingStatus $ ExecutorWaiting Nothing++waitingDesc :: Text -> BackendM ()+waitingDesc = pendingStatus . ExecutorWaiting . Just++submitted :: BackendM ()+submitted = pendingStatus $ ExecutorSubmitted Nothing++submittedDesc :: Text -> BackendM ()+submittedDesc = pendingStatus . ExecutorSubmitted . Just++started :: BackendM ()+started = pendingStatus $ ExecutorStarted Nothing++startedDesc :: Text -> BackendM ()+startedDesc = pendingStatus . ExecutorStarted . Just

@@ -0,0 +1,163 @@+{-# LANGUAGE DeriveGeneric              #-}+{-# LANGUAGE GeneralizedNewtypeDeriving #-}+{-# LANGUAGE LambdaCase                 #-}+{-# LANGUAGE OverloadedStrings          #-}+{-# LANGUAGE ScopedTypeVariables        #-}+{-# LANGUAGE StaticPointers             #-}+{-# LANGUAGE TypeApplications           #-}++module Control.Distributed.Fork.Internal where++--------------------------------------------------------------------------------+import           Control.Concurrent+import           Control.Concurrent.STM+import           Control.Distributed.Closure+import           Control.Monad.Catch+import           Control.Monad.IO.Class+import           Control.Monad.Trans.Reader+import           Data.Binary+import qualified Data.ByteString             as BS+import qualified Data.ByteString.Lazy        as BL+import           Data.Monoid                 ((<>))+import           Data.Text                   (Text)+import qualified Data.Text                   as T+import           Data.Void+import           GHC.Generics+import           System.Environment+import           System.Exit+import           System.IO                   (stdin)+--------------------------------------------------------------------------------++-- |+-- We switch to executor mode only when  @argv[1] == argExecutorMode@.+argExecutorMode :: String+argExecutorMode = "DISTRIBUTED_FORK_EXECUTOR_MODE"++-- |+-- On distributed-fork, we run the same binary both in your machine (called+-- "driver") and in the remote environment (called "executor"). In order for the+-- program to act according to where it is, you should call this function as the+-- first thing in your @main@:+--+-- @+-- main = do+--   initDistributedFork+--   ...+-- @+initDistributedFork :: IO ()+initDistributedFork =+  getArgs >>= \case+    [x]+      | x == argExecutorMode -> vacuous runExecutor+    _ -> return ()++-- |+-- When on executor mode, we expect a serialised ExecutorClosure from `stdin`,+-- run it and exit.+runExecutor :: IO Void+runExecutor =+  BL.hGetContents stdin+    >>= unclosure . decode @ExecutorClosure+    >> exitSuccess++-- |+-- An ExecutorClosure is a serialisable IO action.+type ExecutorClosure = Closure (IO ())++-- |+-- 'Backend' is responsible for running your functions in a remote environment.+--+-- See:+--+--   * 'Control.Distributed.Fork.LocalProcessBackend.localProcessBackend'+--+--   * <http://hackage.haskell.org/package/distributed-fork-aws-lambda distributed-fork-aws-lambda>+newtype Backend = Backend+  { bExecute :: BS.ByteString -> BackendM BS.ByteString+  -- ^ Should run the current binary in the target environment, put the given+  -- string as standard input and return the executables answer on the standard+  -- output.+  }++-- |+-- BackendM is essentially `IO`, but also has the ability to report the status of the+-- executor.+newtype BackendM a =+  BackendM (ReaderT (ExecutorPendingStatus -> IO ()) IO a)+  deriving (Functor, Applicative, Monad, MonadIO, MonadCatch, MonadThrow)++instance Binary a => Binary (ExecutorFinalStatus a)++-- |+-- Given an IO action and a static proof that the result is 'Serializable', this+-- function runs the action using the Backend in a separate thread and returns a+-- 'TVar' holding the 'ExecutorStatus'.+runBackend ::+     Closure (Dict (Serializable i))+  -> Closure (IO i)+  -> Backend+  -> IO (Handle i)+runBackend dict cls (Backend backend) =+  case unclosure dict of+    Dict -> do+      let BackendM m =+            backend $ BL.toStrict $ encode @ExecutorClosure (toExecutorClosure dict cls)+      t <- atomically (newTVar $ ExecutorPending (ExecutorWaiting Nothing))+      _ <-+        forkIO $ do+          r <-+            either+              (\(err :: SomeException) ->+                 ExecutorFailed $+                 "Backend threw an exception: " <> T.pack (show err))+              parseAnswer <$>+            try (runReaderT m (atomically . writeTVar t . ExecutorPending))+          atomically $ writeTVar t (ExecutorFinished r)+          return ()+      return $ Handle t++toExecutorClosure :: Closure (Dict (Serializable a)) -> Closure (IO a) -> Closure (IO ())+toExecutorClosure dict cls =+  case unclosure dict of+    Dict -> static run `cap` dict `cap` cls+  where+    run :: forall a. Dict (Serializable a) -> IO a -> IO ()+    run Dict a =+      (a >>= BL.putStr . encode . ExecutorSucceeded)+        `catch` (\(ex :: SomeException) ->+          BL.putStr . encode . ExecutorFailed @a $+            "Exception from executor: " <> T.pack (show ex))++parseAnswer :: Binary a => BS.ByteString -> ExecutorFinalStatus a+parseAnswer bs =+  case decodeOrFail (BL.fromStrict bs) of+    Left (_, _, err) -> ExecutorFailed $ "Error decoding answer: " <> T.pack err+    Right (_, _, a) -> a++data ExecutorStatus a+  = ExecutorPending ExecutorPendingStatus+  | ExecutorFinished (ExecutorFinalStatus a)++data ExecutorPendingStatus+  = ExecutorWaiting (Maybe Text)+  | ExecutorSubmitted (Maybe Text)+  | ExecutorStarted (Maybe Text)++data ExecutorFinalStatus a+  = ExecutorFailed Text+  | ExecutorSucceeded a+  deriving (Generic)++-- |+-- Result of a 'fork' is an Handle where you can 'await' a result.+newtype Handle a = Handle (TVar (ExecutorStatus a))++tryAwait :: Handle a -> IO (Either Text a)+tryAwait (Handle t) = do+  r <- liftIO . atomically $+    readTVar t >>= \case+      ExecutorPending _ -> retry+      ExecutorFinished a -> return a+  return $ case r of+    ExecutorFailed err  -> Left err+    ExecutorSucceeded a -> Right a

@@ -0,0 +1,18 @@+module Control.Distributed.Fork.LocalProcessBackend where++--------------------------------------------------------------------------------+import qualified Data.ByteString.Lazy               as BL+import           System.Process.Typed+--------------------------------------------------------------------------------+import           Control.Distributed.Fork.Backend+--------------------------------------------------------------------------------++-- |+-- A 'Backend' which uses local processes as executors. Useful for testing.+localProcessBackend :: Backend+localProcessBackend = Backend $ \stdin' -> do+  executable <- liftIO getExecutablePath+  let conf =+        setStdin (byteStringInput $ BL.fromStrict stdin') $+        proc executable [argExecutorMode]+  liftIO . fmap BL.toStrict $ readProcessStdout_ conf

@@ -0,0 +1,82 @@+{-# LANGUAGE LambdaCase #-}++module Control.Distributed.Fork.Utils where++--------------------------------------------------------------------------------+import Control.Monad (forM, unless)+import Control.Concurrent.STM (newTVar, atomically, retry, readTVar, modifyTVar, writeTVar)+import Control.Monad.Trans.State (evalStateT, get, put)+import Control.Monad.IO.Class (liftIO)+import Control.Concurrent.Async (async, wait, waitBoth)+import Control.Exception (throwIO)+import Data.Function (fix)+import Control.Concurrent (threadDelay)+import qualified System.Console.Terminal.Size as TS+--------------------------------------------------------------------------------+import Control.Distributed.Fork.Internal (Handle (..))+import Control.Distributed.Fork+--------------------------------------------------------------------------------++-- |+-- Runs given closures concurrently using the 'Backend' with a progress bar.+--+-- Throws 'ExecutorFailedException' if something fails.+mapConcurrentlyWithProgress :: Backend+                            -> Closure (Dict (Serializable a))+                            -> [Closure (IO a)]+                            -> IO [a]+mapConcurrentlyWithProgress backend dict xs = do+  st <- atomically $ newTVar (True, 0::Int, 0::Int, 0::Int, 0::Int)+  handles <- mapM (fork backend dict) xs+  asyncs <- forM handles $ \(Handle tv) ->+    async . flip evalStateT (0, 0, 0, 0) . fix $ \recurse -> do+      oldState <- get+      (newState, result) <- liftIO $ atomically $ do+        (n, r) <- readTVar tv >>= return . \case+          ExecutorPending (ExecutorWaiting _)   -> ((1, 0, 0, 0), Nothing)+          ExecutorPending (ExecutorSubmitted _) -> ((0, 1, 0, 0), Nothing)+          ExecutorPending (ExecutorStarted _)   -> ((0, 0, 1, 0), Nothing)+          ExecutorFinished fr                   -> ((0, 0, 0, 1), Just fr)+        unless (oldState /= n) retry+        return (n, r)+      put newState+      liftIO . atomically $+        modifyTVar st $ \case+          (_, s1, s2, s3, s4) -> case (oldState, newState) of+            ((o1, o2, o3, o4), (n1, n2, n3, n4)) ->+              (True, s1 - o1 + n1, s2 - o2 + n2, s3 - o3 + n3, s4 - o4 + n4)+      case result of+        Nothing -> recurse+        Just (ExecutorFailed err) -> liftIO . throwIO $ ExecutorFailedException err+        Just (ExecutorSucceeded x) -> return x++  result <- async $ mapM wait asyncs++  termWidth <- maybe 40 TS.width <$> TS.size :: IO Int+  let total = length xs+      ratio = fromIntegral total / fromIntegral (termWidth - 2) :: Double++  pbar <- async . fix $ \recurse -> do+    (waiting, submitted, started, finished) <- atomically $+      readTVar st >>= \case+        (False, _, _, _, _) -> retry+        (True, a, b, c, d) -> do+          writeTVar st (False, a, b, c, d)+          return (a, b, c, d)++    let p c n = replicate (truncate (fromIntegral n / ratio)) c+    putStr . concat $+      [ "\r"+      , "["+      , p '#' finished+      , p ':' started+      , p '.' submitted+      , p ' ' waiting+      , "]"+      ]++    if finished < total+      then threadDelay 10000 >> recurse+      else putStrLn ""++  fst <$> waitBoth result pbar

@@ -0,0 +1,47 @@+{-# LANGUAGE OverloadedStrings #-}+{-# LANGUAGE StaticPointers    #-}++module Main where++--------------------------------------------------------------------------------+import           Control.Exception                              (try)+import           System.Posix.Process                           (getProcessID)+import           Test.Tasty+import           Test.Tasty.HUnit+--------------------------------------------------------------------------------+import           Control.Distributed.Fork+import           Control.Distributed.Fork.LocalProcessBackend+--------------------------------------------------------------------------------++main :: IO ()+main = do+  initDistributedFork+  defaultMain tests++tests :: TestTree+tests =+  testGroup+    "Tests"+    [ testCase "localProcessBackend gives correct result" $ do+        ret <-+          await =<< fork+            localProcessBackend+            (static Dict)+            (static (return (42 :: Integer, "fortytwo" :: String, Just True)))+        ret @?= (42, "fortytwo", Just True)+    , testCase "localProcessBackend actually spawns" $ do+        localPid <- show <$> getProcessID+        remotePid <-+          await =<< fork+            localProcessBackend+            (static Dict)+            (static (show <$> getProcessID))+        remotePid /= localPid @? "Spawned process should have a different PID."+    , testCase "localProcessBackend handles exceptions" $ do+        handle <- fork+          localProcessBackend+          (static Dict)+          (static (return (div 1 0) :: IO Int))+        answer <- try $ await handle+        answer @?= Left (ExecutorFailedException "Exception from executor: divide by zero")+    ]