diff --git a/CHANGELOG.md b/CHANGELOG.md new file mode 100644 --- /dev/null +++ b/CHANGELOG.md @@ -0,0 +1,5 @@ +# Revision history for streamly-fsnotify + +## 1.0.0.0 -- 2019-12-06 + +* First version. Released on an unsuspecting world. diff --git a/LICENSE.md b/LICENSE.md new file mode 100644 --- /dev/null +++ b/LICENSE.md @@ -0,0 +1,675 @@ +### GNU GENERAL PUBLIC LICENSE + +Version 3, 29 June 2007 + +Copyright (C) 2007 Free Software Foundation, Inc. + + +Everyone is permitted to copy and distribute verbatim copies of this +license document, but changing it is not allowed. + +### Preamble + +The GNU General Public License is a free, copyleft license for +software and other kinds of works. + +The licenses for most software and other practical works are designed +to take away your freedom to share and change the works. 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If your program is a subroutine +library, you may consider it more useful to permit linking proprietary +applications with the library. If this is what you want to do, use the +GNU Lesser General Public License instead of this License. But first, +please read . diff --git a/README.md b/README.md new file mode 100644 --- /dev/null +++ b/README.md @@ -0,0 +1,69 @@ +# ``streamly-fsnotify`` + +## What's the deal with this library? + +[``streamly``][1] is an undoubtedly awesome library - [fast][2], flexible, and +well-documented. File system watching is a natural fit for a streaming library, +and this is exactly what ``streamly-notify`` provides you. + +As an example, here is a program which watches ``/home/koz/c-project/`` and any +of its subdirectories for added or modified C source files (which we take to be +anything with a ``.c`` extension). This program then writes that the event +occurred, to what file, and when, forever. + +```haskell + +{-# LANGUAGE LambdaCase #-} + +import Streamly.FSNotify (EventPredicate, + hasExtension, is Directory, invert, isDeletion, conj, + watchTree) +import System.Path (FsPath, FileExt, fromFilePath) + +import qualified Streamly.Prelude as SP + +-- conj -> both must be true +-- invert -> true when the argument would be false and vice versa +isCSourceFile :: EventPredicate +isCSourceFile = hasExtension (FileExt "c") `conj` (invert isDirectory) + +notDeletion :: EventPredicate +notDeletion = invert isDeletion + +srcPath :: FsPath +srcPath = fromFilePath "/home/koz/c-project" + +-- first value given by watchTree stops the watcher +-- we don't use it here, but if you want to, just call it +main :: IO () +main = do (_, stream) <- watchTree srcPath (isCSourceFile `conj` notDeletion) + SP.drain . SP.mapM go $ stream + where go = \case (Added p t _) -> putStrLn ("Created: " ++ show p ++ " at " ++ show t) + (Modified p t _) -> putStrLn ("Modified: " ++ show p ++ " at " ++ show t) + _ -> pure () +``` + +## That seems pretty cool! What kind of features can I expect? + +* Cross-platform - should work anywhere both ``streamly`` and ``fsnotify`` do. +* Efficient (event-driven, so won't shred your CPU or load your RAM). +* Able to do one-level and recursive watching. +* Extensive set of filtering predicates, so you don't have to see events you + don't care about! +* Compositional and principled treatment of file paths and event filtering + predicates. + +## Sounds good? Can I use it? + +We've test-built this library for GHCs 8.2.2 through 8.8.1 on GNU/Linux. In +theory, ``streamly-fsnotify`` should work everywhere both ``streamly`` and +``fsnotify`` will, which includes older GHCs (7.10) and other OSes (such as +Windows). However, we haven't tried it ourselves - let us know if you do! + +## License + +This library is under the GNU General Public License, version 3 or later (SPDX +code ``GPL-3.0-or-later``). For more details, see the ``LICENSE.md`` file. + +[1]: http://hackage.haskell.org/package/streamly +[2]: https://github.com/composewell/streaming-benchmarks diff --git a/Setup.hs b/Setup.hs new file mode 100644 --- /dev/null +++ b/Setup.hs @@ -0,0 +1,3 @@ +import Distribution.Simple + +main = defaultMain diff --git a/src/Streamly/FSNotify.hs b/src/Streamly/FSNotify.hs new file mode 100644 --- /dev/null +++ b/src/Streamly/FSNotify.hs @@ -0,0 +1,296 @@ +{- + - Copyright (C) 2019 Koz Ross + - + - This program is free software: you can redistribute it and/or modify + - it under the terms of the GNU General Public License as published by + - the Free Software Foundation, either version 3 of the License, or + - (at your option) any later version. + - + - This program is distributed in the hope that it will be useful, + - but WITHOUT ANY WARRANTY; without even the implied warranty of + - MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + - GNU General Public License for more details. + - + - You should have received a copy of the GNU General Public License + - along with this program. If not, see . + -} + +{-# LANGUAGE Trustworthy #-} +{-# LANGUAGE LambdaCase #-} +{-# LANGUAGE FlexibleContexts #-} + +-- | +-- Module: Streamly.FSNotify +-- Description: Filesystem watching as Streamly streams. +-- Copyright: (C) Koz Ross 2019 +-- License: GPL version 3.0 or later +-- Maintainer: koz.ross@retro-freedom.nz +-- Stability: Experimental +-- Portability: GHC only +-- +-- __Introduction__ +-- +-- This provides file watching as a Streamly stream. You can either watch +-- recursively (namely, a directory's contents and all its subdirectories as +-- well), or not. You can also filter out file system events you are not +-- interested in. Lastly, we provide a compositional scheme for constructing +-- filters for file system events. +-- +-- __Example__ +-- +-- This example program watches @\/home\/koz\/c-project@ (and any of its +-- subdirectories) for added or modified +-- files with a @.c@ extension, and emits the change to the terminal, along with a +-- timestamp of when it happened, forever: +-- +-- > {-# LANGUAGE LambdaCase #-} +-- > +-- > import Streamly.FSNotify (EventPredicate, +-- > hasExtension, isDirectory, invert, isDeletion, conj, +-- > watchTree) +-- > import System.Path (FsPath, FileExt, fromFilePath) +-- > +-- > import qualified Streamly.Prelude as SP +-- > +-- > -- conj -> both must be true +-- > -- invert -> true when the argument would be false and vice versa +-- > isCSourceFile :: EventPredicate +-- > isCSourceFile = hasExtension (FileExt "c") `conj` (invert isDirectory) +-- > +-- > notDeletion :: EventPredicate +-- > notDeletion = invert isDeletion +-- > +-- > srcPath :: FsPath +-- > srcPath = fromFilePath "/home/koz/c-project" +-- > +-- > -- first value given by watchTree stops the watcher +-- > -- we don't use it here, but if you want to, just call it +-- > main :: IO () +-- > main = do (_, stream) <- watchTree srcPath (isCSourceFile `conj` notDeletion) +-- > SP.drain . SP.mapM go $ stream +-- > where go = \case (Added p t _) -> putStrLn ("Created: " ++ show p ++ " at " ++ show t) +-- > (Modified p t _) -> putStrLn ("Modified: " ++ show p ++ " at " ++ show t) +-- > _ -> pure () +module Streamly.FSNotify +( + -- * Basic types + FSEntryType(..), Event(..), StopWatching, + eventPath, eventTime, eventFSEntry, + -- * Events and predicates + EventPredicate(..), + isDirectory, hasExtension, isCreation, isModification, isDeletion, isBasic, invert, conj, disj, + -- * Watchers + watchDirectory, watchDirectoryWith, watchTree, watchTreeWith +) where + +import Data.Semiring (Semiring(..)) +import Control.Concurrent.Chan (newChan, readChan) +import Streamly (IsStream, MonadAsync) +import Control.Monad.IO.Class (MonadIO(..)) +import Data.Bool (bool) +import Data.Time.Clock (UTCTime) +import Data.Text (Text, pack) +import System.Path (Path, FsPath(..), FileExt, Absolute, + isExtensionOf, toFilePath, makeAbsolute, fromAbsoluteFilePath) + +import qualified Streamly.Prelude as SP +import qualified System.FSNotify as FSN + +-- | Allows us to designate 'Event's as being fired by a directory or a +-- non-directory entry. +data FSEntryType = Dir | NotDir + deriving (Eq, Show, Read, Bounded, Enum) + +-- | A file system notification. +data Event = Added (Path Absolute) UTCTime FSEntryType -- ^ Creation event + | Modified (Path Absolute) UTCTime FSEntryType -- ^ Modification event + | Removed (Path Absolute) UTCTime FSEntryType -- ^ Deletion event + | Other (Path Absolute) UTCTime Text -- ^ Some other kind of event + deriving (Eq, Show) + +-- | A function, which, when executed, stops a file system watch. +type StopWatching m = m () + +-- | Helper to retrieve the file path associated with an event. +{-# INLINE eventPath #-} +eventPath :: Event -> FsPath +eventPath (Added p _ _) = FsPath p +eventPath (Modified p _ _) = FsPath p +eventPath (Removed p _ _) = FsPath p +eventPath (Other p _ _) = FsPath p + +-- | Helper to retrieve an event's timestamp. +{-# INLINE eventTime #-} +eventTime :: Event -> UTCTime +eventTime (Added _ t _) = t +eventTime (Modified _ t _) = t +eventTime (Removed _ t _) = t +eventTime (Other _ t _) = t + +-- | Helper to retrieve whether the event stems from a directory or not. +-- Returns 'Nothing' if the event is not \'basic\' (that is, not a creation, +-- modification or deletion). +{-# INLINE eventFSEntry #-} +eventFSEntry :: Event -> Maybe FSEntryType +eventFSEntry (Added _ _ e) = Just e +eventFSEntry (Modified _ _ e) = Just e +eventFSEntry (Removed _ _ e) = Just e +eventFSEntry Other{} = Nothing + +-- Predicates + +-- | A \'test\' for whether we want to \'notice\' an event. Should return 'True' +-- for events we care about. +newtype EventPredicate = EventPredicate { runPredicate :: Event -> Bool } + +-- | 'EventPredicate' can be a 'Semigroup' in two ways: +-- +-- - Under logical conjunction (both of the conditions must be met); and +-- - Under logical disjunction (either of the conditions must be met). +-- +-- Both of these can be made into a 'Monoid' by using the trivial predicate +-- (always true) for the first case, and the null predicate (always false) for +-- the second. This makes it a valid candidate to be a semiring, which allows +-- our users to compose 'EventPredicate's using both of these methods, as they +-- see fit. +-- +-- If you want an instance of 'Semigroup' and 'Monoid' with one of these +-- behaviours, you can use 'Data.Semiring.Add' (for the logical disjunction +-- behaviour) or 'Data.Semiring.Mul' (for the logical conjunction behaviour). +instance Semiring EventPredicate where + {-# INLINE plus #-} + (EventPredicate f) `plus` (EventPredicate g) = EventPredicate ((||) <$> f <*> g) + {-# INLINE zero #-} + zero = nothing + {-# INLINE times #-} + (EventPredicate f) `times` (EventPredicate g) = EventPredicate ((&&) <$> f <*> g) + {-# INLINE one #-} + one = everything + +-- | Predicate conjunction (meaning that /both/ have to be true for the result +-- to be true). Synonym for 'Data.Semigroup.times'. +{-# INLINE conj #-} +conj :: EventPredicate -> EventPredicate -> EventPredicate +conj = times + +-- | Predicate disjunction (meaning that /either/ has to be true for the result +-- to be true). Synonym for 'Data.Semigroup.plus'. +{-# INLINE disj #-} +disj :: EventPredicate -> EventPredicate -> EventPredicate +disj = plus + +-- | The trivial predicate (allows any event through). +{-# INLINE everything #-} +everything :: EventPredicate +everything = EventPredicate . const $ True + +-- | The null predicate (allows no events through). +{-# INLINE nothing #-} +nothing :: EventPredicate +nothing = EventPredicate . const $ False + +-- | Allows through events that are caused by directories. +-- Note that this will assume that non-\'basic\' events (that is, not creations, +-- modifications or deletions) do not stem from directories; use with care. +{-# INLINE isDirectory #-} +isDirectory :: EventPredicate +isDirectory = EventPredicate $ \e -> case eventFSEntry e of + Nothing -> False + Just Dir -> True + Just NotDir -> False + +-- | Allows through events triggered by file system entries with a specific +-- extension. +{-# INLINE hasExtension #-} +hasExtension :: FileExt -> EventPredicate +hasExtension fe = EventPredicate $ \case + (Added p _ _) -> isExtensionOf fe p + (Modified p _ _) -> isExtensionOf fe p + (Removed p _ _) -> isExtensionOf fe p + (Other p _ _) -> isExtensionOf fe p + +-- | Allows through only creation events. +{-# INLINE isCreation #-} +isCreation :: EventPredicate +isCreation = EventPredicate $ \case + Added{} -> True + _ -> False + +-- | Allows through only modification events. +{-# INLINE isModification #-} +isModification :: EventPredicate +isModification = EventPredicate $ \case + Modified{} -> True + _ -> False + +-- | Allows through only deletion events. +{-# INLINE isDeletion #-} +isDeletion :: EventPredicate +isDeletion = EventPredicate $ \case + Removed{} -> True + _ -> False + +-- | Allows through only \'basic\' events (namely creation, modification and +-- deletion). +{-# INLINE isBasic #-} +isBasic :: EventPredicate +isBasic = EventPredicate $ \case + Other{} -> False + _ -> True + +-- | \'Flips\' the predicate - what it used to allow through is now blocked, and +-- vice versa. +{-# INLINE invert #-} +invert :: EventPredicate -> EventPredicate +invert (EventPredicate f) = EventPredicate (not . f) + +-- Watchers + +-- | Watch a given directory, but only at one level (thus, subdirectories will +-- __not__ be watched recursively). +{-# INLINE watchDirectory #-} +watchDirectory :: (IsStream t, MonadAsync m) => FsPath -> EventPredicate -> m (StopWatching m, t m Event) +watchDirectory = watch FSN.watchDirChan FSN.defaultConfig + +-- | As 'watchDirectory', but with a specified set of watch options. +{-# INLINE watchDirectoryWith #-} +watchDirectoryWith :: (IsStream t, MonadAsync m) => FSN.WatchConfig -> FsPath -> EventPredicate -> m (StopWatching m, t m Event) +watchDirectoryWith = watch FSN.watchDirChan + +-- | Watch a given directory recursively (thus, subdirectories will also have +-- their contents watched). +{-# INLINE watchTree #-} +watchTree :: (IsStream t, MonadAsync m) => FsPath -> EventPredicate -> m (StopWatching m, t m Event) +watchTree = watch FSN.watchTreeChan FSN.defaultConfig + +-- | As 'watchTree', but with a specified set of watch options. +{-# INLINE watchTreeWith #-} +watchTreeWith :: (IsStream t, MonadAsync m) => FSN.WatchConfig -> FsPath -> EventPredicate -> m (StopWatching m, t m Event) +watchTreeWith = watch FSN.watchTreeChan + +-- Helpers +{-# INLINE watch #-} +watch :: (IsStream t, MonadAsync m) => + (FSN.WatchManager -> FilePath -> FSN.ActionPredicate -> FSN.EventChannel -> IO FSN.StopListening) -> + FSN.WatchConfig -> + FsPath -> EventPredicate -> m (StopWatching m, t m Event) +watch f conf p predicate = do + manager <- liftIO . FSN.startManagerConf $ conf + fp <- toFilePath <$> (liftIO . makeAbsolute $ p) + let pred' = runPredicate predicate . mungeEvent + chan <- liftIO newChan + stop <- liftIO . f manager fp pred' $ chan + let reallyStop = liftIO stop >> liftIO (FSN.stopManager manager) + pure (reallyStop, SP.repeatM (liftIO . fmap mungeEvent . readChan $ chan)) + +{-# INLINE mungeEvent #-} +mungeEvent :: FSN.Event -> Event +mungeEvent = \case + (FSN.Added p t b) -> Added (fromAbsoluteFilePath p) t (isDir b) + (FSN.Modified p t b) -> Modified (fromAbsoluteFilePath p) t (isDir b) + (FSN.Removed p t b) -> Modified (fromAbsoluteFilePath p) t (isDir b) + (FSN.Unknown p t s) -> Other (fromAbsoluteFilePath p) t (pack s) + +{-# INLINE isDir #-} +isDir :: Bool -> FSEntryType +isDir = bool NotDir Dir diff --git a/streamly-fsnotify.cabal b/streamly-fsnotify.cabal new file mode 100644 --- /dev/null +++ b/streamly-fsnotify.cabal @@ -0,0 +1,33 @@ +cabal-version: 2.2 +name: streamly-fsnotify +-- PVP summary: +-+------- breaking API changes +-- | | +----- non-breaking API additions +-- | | | +--- code changes with no API change +version: 1.0.0.0 +synopsis: Folder watching as a Streamly stream. +description: Provides Streamly streams for both single-level and + recursive folder watching. Also contains a principled and + compositional system for filtering file system events. +homepage: https://notabug.org/koz.ross/streamly-fsnotify +license: GPL-3.0-or-later +license-file: LICENSE.md +author: Koz Ross +maintainer: koz.ross@retro-freedom.nz +copyright: (C) Koz Ross 2019 +category: Streamly +tested-with: GHC == 8.6.5 +build-type: Simple +extra-source-files: CHANGELOG.md, + README.md + +library + exposed-modules: Streamly.FSNotify + build-depends: base >= 4.9 && < 5, + streamly >= 0.7.0 && < 0.8.0, + fsnotify >= 0.3.0.1 && < 0.4.0.0, + paths >= 0.2.0.0 && < 0.3.0.0, + semirings >= 0.5.2 && < 0.6.0, + text >= 1.2.4.0 && < 1.3.0.0, + time >= 1.9.3 && < 2.0.0 + hs-source-dirs: src + default-language: Haskell2010