diff --git a/LICENSE b/LICENSE new file mode 100644 --- /dev/null +++ b/LICENSE @@ -0,0 +1,22 @@ +Copyright (c) 2018, Nikita Volkov + +Permission is hereby granted, free of charge, to any person +obtaining a copy of this software and associated documentation +files (the "Software"), to deal in the Software without +restriction, including without limitation the rights to use, +copy, modify, merge, publish, distribute, sublicense, and/or sell +copies of the Software, and to permit persons to whom the +Software is furnished to do so, subject to the following +conditions: + +The above copyright notice and this permission notice shall be +included in all copies or substantial portions of the Software. + +THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, +EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES +OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND +NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT +HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, +WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING +FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR +OTHER DEALINGS IN THE SOFTWARE. diff --git a/Setup.hs b/Setup.hs new file mode 100644 --- /dev/null +++ b/Setup.hs @@ -0,0 +1,2 @@ +import Distribution.Simple +main = defaultMain diff --git a/futures.cabal b/futures.cabal new file mode 100644 --- /dev/null +++ b/futures.cabal @@ -0,0 +1,29 @@ +name: futures +version: 0.1 +synopsis: Simple and fast implementation of Future +category: Futures, Concurrency +homepage: https://github.com/nikita-volkov/futures +bug-reports: https://github.com/nikita-volkov/futures/issues +author: Nikita Volkov +maintainer: Nikita Volkov +copyright: (c) 2018, Nikita Volkov +license: MIT +license-file: LICENSE +build-type: Simple +cabal-version: >=1.10 +tested-with: GHC ==8.4.2, GHC ==8.6.* + +source-repository head + type: git + location: git://github.com/nikita-volkov/futures.git + +library + hs-source-dirs: library + default-extensions: Arrows, BangPatterns, ConstraintKinds, DataKinds, DefaultSignatures, DeriveDataTypeable, DeriveFoldable, DeriveFunctor, DeriveGeneric, DeriveTraversable, EmptyDataDecls, FlexibleContexts, FlexibleInstances, FunctionalDependencies, GADTs, GeneralizedNewtypeDeriving, LambdaCase, LiberalTypeSynonyms, MagicHash, MultiParamTypeClasses, MultiWayIf, NoImplicitPrelude, NoMonomorphismRestriction, OverloadedStrings, PatternGuards, PatternSynonyms, ParallelListComp, QuasiQuotes, RankNTypes, RecordWildCards, ScopedTypeVariables, StandaloneDeriving, TemplateHaskell, TupleSections, TypeFamilies, TypeOperators, UnboxedTuples + default-language: Haskell2010 + exposed-modules: + Futures + other-modules: + Futures.Prelude + build-depends: + base >=4.11 && <5 diff --git a/library/Futures.hs b/library/Futures.hs new file mode 100644 --- /dev/null +++ b/library/Futures.hs @@ -0,0 +1,40 @@ +module Futures +( + Future, + fork, + block, +) +where + +import Futures.Prelude + + +{-| +Abstraction over a pattern where you delegate an IO action to be executed on another thread, +but are still interested in processing its result some time later on. +In the meantime you can execute other actions. +IOW, it is an implementation of asynchronous programming pattern. + +Another way to look at future is as on an evaluate-once computation. +-} +newtype Future a = Future (IO a) deriving (Functor, Applicative, Monad, MonadIO, MonadFail) + +{-| +Fork a thread to execute the computation on and produce a future, +which will provide its results. + +The IO action must not throw exceptions! If you want to transfer them, wrap it in 'try'. +-} +fork :: IO a -> IO (Future a) +fork io = do + mv <- newEmptyMVar + forkIO $ do + a <- io + putMVar mv a + return $ Future $ readMVar mv + +{-| +Block waiting until the future result is available. +-} +block :: Future a -> IO a +block (Future io) = io diff --git a/library/Futures/Prelude.hs b/library/Futures/Prelude.hs new file mode 100644 --- /dev/null +++ b/library/Futures/Prelude.hs @@ -0,0 +1,92 @@ +module Futures.Prelude +( + module Exports, + modifyTVar', + Product2(..), + forkIOWithoutHandler, +) +where + +-- base +------------------------- +import Control.Applicative as Exports +import Control.Arrow as Exports +import Control.Category as Exports +import Control.Concurrent as Exports +import Control.Exception as Exports +import Control.Monad as Exports hiding (mapM_, sequence_, forM_, msum, mapM, sequence, forM, fail) +import Control.Monad.Fail as Exports +import Control.Monad.IO.Class as Exports +import Control.Monad.Fix as Exports hiding (fix) +import Control.Monad.ST as Exports +import Data.Bits as Exports +import Data.Bool as Exports +import Data.Char as Exports +import Data.Coerce as Exports +import Data.Complex as Exports +import Data.Data as Exports +import Data.Dynamic as Exports +import Data.Either as Exports +import Data.Fixed as Exports +import Data.Foldable as Exports +import Data.Function as Exports hiding (id, (.)) +import Data.Functor as Exports +import Data.Int as Exports +import Data.IORef as Exports +import Data.Ix as Exports +import Data.List as Exports hiding (sortOn, isSubsequenceOf, uncons, concat, foldr, foldl1, maximum, minimum, product, sum, all, and, any, concatMap, elem, foldl, foldr1, notElem, or, find, maximumBy, minimumBy, mapAccumL, mapAccumR, foldl') +import Data.Maybe as Exports +import Data.Monoid as Exports hiding (Last(..), First(..)) +import Data.Ord as Exports +import Data.Proxy as Exports +import Data.Ratio as Exports +import Data.STRef as Exports +import Data.String as Exports +import Data.Traversable as Exports +import Data.Tuple as Exports +import Data.Unique as Exports +import Data.Version as Exports +import Data.Word as Exports +import Debug.Trace as Exports +import Foreign.ForeignPtr as Exports +import Foreign.Ptr as Exports +import Foreign.StablePtr as Exports +import Foreign.Storable as Exports hiding (sizeOf, alignment) +import GHC.Conc as Exports hiding (withMVar, threadWaitWriteSTM, threadWaitWrite, threadWaitReadSTM, threadWaitRead) +import GHC.Exts as Exports (lazy, inline, sortWith, groupWith, Int(I#), fork#, forkOn#) +import GHC.Generics as Exports (Generic) +import GHC.IO (IO(IO)) +import GHC.IO.Exception as Exports +import Numeric as Exports +import Prelude as Exports hiding (fail, concat, foldr, mapM_, sequence_, foldl1, maximum, minimum, product, sum, all, and, any, concatMap, elem, foldl, foldr1, notElem, or, mapM, sequence, id, (.)) +import System.Environment as Exports +import System.Exit as Exports +import System.IO as Exports +import System.IO.Error as Exports +import System.IO.Unsafe as Exports +import System.Mem as Exports +import System.Mem.StableName as Exports +import System.Timeout as Exports +import Text.ParserCombinators.ReadP as Exports (ReadP, ReadS, readP_to_S, readS_to_P) +import Text.ParserCombinators.ReadPrec as Exports (ReadPrec, readPrec_to_P, readP_to_Prec, readPrec_to_S, readS_to_Prec) +import Text.Printf as Exports (printf, hPrintf) +import Text.Read as Exports (Read(..), readMaybe, readEither) +import Unsafe.Coerce as Exports + + +-- | Strict version of 'modifyTVar'. +{-# INLINE modifyTVar' #-} +modifyTVar' :: TVar a -> (a -> a) -> STM () +modifyTVar' var f = do + x <- readTVar var + writeTVar var $! f x + +data Product2 a b = Product2 !a !b deriving (Eq) + +-- | +-- A more efficient version of 'forkIO', +-- which does not install a default exception handler on the forked thread. +{-# INLINE forkIOWithoutHandler #-} +forkIOWithoutHandler :: IO () -> IO ThreadId +forkIOWithoutHandler action = + IO $ \s -> case (fork# action s) of (# s', tid #) -> (# s', ThreadId tid #)