Import

.gitignore

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+dist
+dist-*
+cabal-dev
+*.o
+*.hi
+*.chi
+*.chs.h
+*.dyn_o
+*.dyn_hi
+.hpc
+.hsenv
+.cabal-sandbox/
+cabal.sandbox.config
+*.prof
+*.aux
+*.hp
+*.eventlog
+.stack-work/
+cabal.project.local

LICENSE

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+Copyright Moritz Schulte (c) 2016, 2017
+
+All rights reserved.
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are met:
+
+    * Redistributions of source code must retain the above copyright
+      notice, this list of conditions and the following disclaimer.
+
+    * Redistributions in binary form must reproduce the above
+      copyright notice, this list of conditions and the following
+      disclaimer in the documentation and/or other materials provided
+      with the distribution.
+
+    * Neither the name of Author name here nor the names of other
+      contributors may be used to endorse or promote products derived
+      from this software without specific prior written permission.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

README.md

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+# async-timer
+
+Example:
+
+      let conf = defaultTimerConf & timerConfSetInitDelay  500 -- 500 ms
+                                  & timerConfSetInterval  1000 -- 1 s
+
+      withAsyncTimer conf $ \ timer -> do
+        forM_ [1..10] $ \_ -> do
+          timerWait timer
+          putStrLn "Tick"

Setup.hs

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+import Distribution.Simple
+main = defaultMain

async-timer.cabal

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+name:                async-timer
+version:             0.1.2
+synopsis:            Support for timer based execution of IO actions
+description:         Please see README.md
+homepage:            https://github.com/mtesseract/async-timer
+license:             BSD3
+license-file:        LICENSE
+author:              Moritz Schulte
+maintainer:          [email protected]
+copyright:           2016, 2017 Moritz Schulte
+category:            Concurrency
+build-type:          Simple
+extra-source-files:  README.md
+cabal-version:       >=1.10
+
+library
+  hs-source-dirs:      src
+  exposed-modules:     Control.Concurrent.Async.Timer
+                     , Control.Concurrent.Async.Timer.Unsafe
+  other-modules:       Control.Concurrent.Async.Timer.Internal
+  build-depends:       base >= 4.7 && < 5
+                     , lifted-async
+                     , classy-prelude
+  default-language:    Haskell2010
+  default-extensions:  NoImplicitPrelude
+  ghc-options:         -Wall
+
+test-suite async-timer-test
+  type:                exitcode-stdio-1.0
+  hs-source-dirs:      test
+  main-is:             Spec.hs
+  build-depends:       base
+                     , classy-prelude
+                     , async-timer
+                     , HUnit
+                     , test-framework
+                     , test-framework-hunit
+                     , containers
+                     , criterion
+  ghc-options:         -threaded -rtsopts -with-rtsopts=-N
+  default-language:    Haskell2010
+  default-extensions:  NoImplicitPrelude
+                     , OverloadedStrings
+
+source-repository head
+  type:     git
+  location: https://github.com/mtesseract/async-timer

src/Control/Concurrent/Async/Timer.hs

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+{-# LANGUAGE FlexibleContexts      #-}
+{-# LANGUAGE MultiParamTypeClasses #-}
+{-# LANGUAGE RankNTypes            #-}
+
+module Control.Concurrent.Async.Timer
+  ( Timer
+  , defaultTimerConf
+  , timerConfSetInitDelay
+  , timerConfSetInterval
+  , withAsyncTimer
+  , timerWait
+  ) where
+
+import           ClassyPrelude
+import           Control.Concurrent.Async.Timer.Internal
+
+withAsyncTimer :: forall m b. (MonadBaseControl IO m, Forall (Pure m))
+               => TimerConf -> (Timer -> m b) -> m b
+withAsyncTimer conf io = do
+  mVar <- newEmptyMVar
+  let timer        = Timer { timerMVar = mVar }
+      timerTrigger = void $ tryPutMVar mVar ()
+      initDelay'   = toMicroseconds $ _timerConfInitDelay conf
+      interval'    = toMicroseconds $ _timerConfInterval  conf
+      timerThread  = timerLoop (threadDelay initDelay')
+                               (threadDelay interval')
+                               timerTrigger
+  withAsync timerThread $ const (io timer)
+
+  where toMicroseconds x = x * (10 ^ (3 :: Int))

src/Control/Concurrent/Async/Timer/Internal.hs

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+{-# LANGUAGE FlexibleContexts         #-}
+{-# LANGUAGE ForeignFunctionInterface #-}
+{-# LANGUAGE InterruptibleFFI         #-}
+{-# LANGUAGE MultiParamTypeClasses    #-}
+
+module Control.Concurrent.Async.Timer.Internal where
+
+import           ClassyPrelude
+
+-- | Sleep 'dt' milliseconds.
+millisleep :: Int64 -> IO ()
+millisleep dt = threadDelay (fromIntegral dt * 10 ^ (3 :: Int))
+
+data TimerConf = TimerConf { _timerConfInitDelay :: Int
+                           , _timerConfInterval  :: Int }
+
+defaultTimerConf :: TimerConf
+defaultTimerConf = TimerConf { _timerConfInitDelay =    0
+                             , _timerConfInterval  = 1000 }
+
+timerConfSetInitDelay :: Int -> TimerConf -> TimerConf
+timerConfSetInitDelay n conf = conf { _timerConfInitDelay = n }
+
+timerConfSetInterval :: Int -> TimerConf -> TimerConf
+timerConfSetInterval n conf = conf { _timerConfInterval = n }
+
+data Timer = Timer { timerMVar :: MVar () }
+
+timerLoop :: MonadBaseControl IO m
+          => m () -> m () -> m () -> m ()
+timerLoop initDelay intervalDelay timerTrigger = do
+  initDelay
+  forever $ timerTrigger >> intervalDelay
+
+timerWait :: MonadBaseControl IO m
+          => Timer -> m ()
+timerWait = void . takeMVar . timerMVar

src/Control/Concurrent/Async/Timer/Unsafe.hs

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+{-# LANGUAGE FlexibleContexts      #-}
+{-# LANGUAGE MultiParamTypeClasses #-}
+{-# LANGUAGE RankNTypes            #-}
+
+module Control.Concurrent.Async.Timer.Unsafe
+  ( Timer
+  , defaultTimerConf
+  , timerConfSetInitDelay
+  , timerConfSetInterval
+  , withAsyncTimer
+  , timerWait
+  ) where
+
+import           ClassyPrelude
+import qualified Control.Concurrent.Async.Lifted         as Unsafe
+import           Control.Concurrent.Async.Timer.Internal
+
+withAsyncTimer :: forall m b. (MonadBaseControl IO m)
+               => TimerConf -> (Timer -> m b) -> m b
+withAsyncTimer conf io = do
+  mVar <- newEmptyMVar
+  let timer        = Timer { timerMVar = mVar }
+      timerTrigger = void $ tryPutMVar mVar ()
+      initDelay'   = toMicroseconds $ _timerConfInitDelay conf
+      interval'    = toMicroseconds $ _timerConfInterval  conf
+      timerThread  = timerLoop (threadDelay initDelay')
+                               (threadDelay interval')
+                               timerTrigger
+  Unsafe.withAsync timerThread $ const (io timer)
+
+  where toMicroseconds x = x * (10 ^ (3 :: Int))

stack.yaml

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+# This file was automatically generated by 'stack init'
+#
+# Some commonly used options have been documented as comments in this file.
+# For advanced use and comprehensive documentation of the format, please see:
+# http://docs.haskellstack.org/en/stable/yaml_configuration/
+
+# Resolver to choose a 'specific' stackage snapshot or a compiler version.
+# A snapshot resolver dictates the compiler version and the set of packages
+# to be used for project dependencies. For example:
+#
+# resolver: lts-3.5
+# resolver: nightly-2015-09-21
+# resolver: ghc-7.10.2
+# resolver: ghcjs-0.1.0_ghc-7.10.2
+# resolver:
+#  name: custom-snapshot
+#  location: "./custom-snapshot.yaml"
+resolver: lts-8.5
+
+# User packages to be built.
+# Various formats can be used as shown in the example below.
+#
+# packages:
+# - some-directory
+# - https://example.com/foo/bar/baz-0.0.2.tar.gz
+# - location:
+#    git: https://github.com/commercialhaskell/stack.git
+#    commit: e7b331f14bcffb8367cd58fbfc8b40ec7642100a
+# - location: https://github.com/commercialhaskell/stack/commit/e7b331f14bcffb8367cd58fbfc8b40ec7642100a
+#   extra-dep: true
+#  subdirs:
+#  - auto-update
+#  - wai
+#
+# A package marked 'extra-dep: true' will only be built if demanded by a
+# non-dependency (i.e. a user package), and its test suites and benchmarks
+# will not be run. This is useful for tweaking upstream packages.
+packages:
+- '.'
+# Dependency packages to be pulled from upstream that are not in the resolver
+# (e.g., acme-missiles-0.3)
+extra-deps: []
+
+# Override default flag values for local packages and extra-deps
+flags: {}
+
+# Extra package databases containing global packages
+extra-package-dbs: []
+
+# Control whether we use the GHC we find on the path
+# system-ghc: true
+#
+# Require a specific version of stack, using version ranges
+# require-stack-version: -any # Default
+# require-stack-version: ">=1.2"
+#
+# Override the architecture used by stack, especially useful on Windows
+# arch: i386
+# arch: x86_64
+#
+# Extra directories used by stack for building
+# extra-include-dirs: [/path/to/dir]
+# extra-lib-dirs: [/path/to/dir]
+#
+# Allow a newer minor version of GHC than the snapshot specifies
+# compiler-check: newer-minor

test/Spec.hs

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+module Main where
+
+import ClassyPrelude
+import Data.Function ((&))
+import Test.Framework (Test, defaultMain, testGroup)
+import Test.Framework.Providers.HUnit (testCase)
+import Test.HUnit ((@?=))
+import Criterion.Measurement
+import Control.Concurrent.Async.Timer
+import Data.Typeable
+
+data MyException = MyException
+    deriving (Show, Typeable)
+
+instance Exception MyException
+
+main :: IO ()
+main = do
+  cap <- getNumCapabilities
+  putStrLn ""
+  putStrLn $ "Cap = " ++ tshow cap
+  defaultMain tests
+
+tests :: [Test.Framework.Test]
+tests =
+  [ testGroup "1st Test Group"
+    [ testCase "1st Test" test1 ]
+  ]
+
+test1 :: IO ()
+test1 = do
+  let conf = defaultTimerConf & timerConfSetInitDelay    0
+                              & timerConfSetInterval  1000 -- ms
+
+  counter <- newIORef 0
+  times <- newIORef []
+
+  withAsyncTimer conf $ \ timer -> do
+    forM_ [1..10] $ \_ -> do
+      timerWait timer
+      void $ fork $ myAction counter times
+
+  threadDelay 1000
+  n <- readIORef counter
+  n @?= 10
+
+  ts <- readIORef times
+  let deltas = case ts of
+                 []         -> []
+                 _ : tsTail -> map (\ (a, b) -> a - b) $ zip ts tsTail
+
+      diff   = sum deltas - 9
+  forM_ deltas (\ dt -> putStrLn $ "dt = " ++ tshow dt)
+  putStrLn $ "average dt = " ++ tshow diff
+  return ()
+
+  where myAction :: IORef Int -> IORef [Double] -> IO ()
+        myAction counter times = do
+          t <- getTime
+          n <- readIORef counter
+          if n == 10
+             then throwIO MyException
+             else return ()
+          let n' = n + 1
+          writeIORef counter n'
+          modifyIORef times (t :)
+          putStrLn $ "Tick no. " ++ tshow n' ++ " (t = " ++ tshow t ++ ")"
+          threadDelay 500000