95 lines
3.4 KiB
Haskell
95 lines
3.4 KiB
Haskell
{-# LANGUAGE CPP #-}
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module Utility.Inotify where
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import Common hiding (isDirectory)
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import System.INotify
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import qualified System.Posix.Files as Files
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import System.Posix.Terminal
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import Control.Concurrent.MVar
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import System.Posix.Signals
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demo :: IO ()
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demo = withINotify $ \i -> do
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watchDir i (const True) (Just add) (Just del) "/home/joey/tmp/me"
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putStrLn "started"
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waitForTermination
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where
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add file = putStrLn $ "add " ++ file
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del file = putStrLn $ "del " ++ file
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{- Watches for changes to files in a directory, and all its subdirectories
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- that match a test, using inotify. This function returns after its initial
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- setup is complete, leaving a thread running. Then callbacks are made for
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- adding and deleting files.
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-
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- Inotify is weak at recursive directory watching; the whole directory
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- tree must be walked and watches set explicitly for each subdirectory.
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-
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- To notice newly created subdirectories, inotify is used, and
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- watches are registered for those directories. There is a race there;
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- things can be added to a directory before the watch gets registered.
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-
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- To close the inotify race, each time a new directory is found, it also
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- recursively scans it, assuming all files in it were just added,
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- and registering each subdirectory.
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-
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- Note: Due to the race amelioration, multiple add events may occur
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- for the same file.
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-
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- Note: Moving a file may involve deleting it from its old location and
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- adding it to the new location.
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-
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- Note: Modification of files is not detected, and it's assumed that when
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- a file that was open for write is closed, it's done being written
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- to, and can be added.
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-
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- Note: inotify has a limit to the number of watches allowed,
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- /proc/sys/fs/inotify/max_user_watches (default 8192).
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- So This will fail if there are too many subdirectories.
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-}
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watchDir :: INotify -> (FilePath -> Bool) -> Maybe (FilePath -> IO ()) -> Maybe (FilePath -> IO ()) -> FilePath -> IO ()
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watchDir i test add del dir = watchDir' False i test add del dir
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watchDir' :: Bool -> INotify -> (FilePath -> Bool) -> Maybe (FilePath -> IO ()) -> Maybe (FilePath -> IO ()) -> FilePath -> IO ()
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watchDir' scan i test add del dir = do
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if test dir
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then void $ do
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_ <- addWatch i watchevents dir go
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mapM walk =<< dirContents dir
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else noop
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where
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watchevents
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| isJust add && isJust del =
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[Create, MoveIn, MoveOut, Delete, CloseWrite]
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| isJust add = [Create, MoveIn, CloseWrite]
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| isJust del = [Create, MoveOut, Delete]
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| otherwise = [Create]
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recurse = watchDir' scan i test add del
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walk f = ifM (catchBoolIO $ Files.isDirectory <$> getFileStatus f)
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( recurse f
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, when (scan && isJust add) $ fromJust add f
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)
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go (Created { isDirectory = False }) = noop
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go (Created { filePath = subdir }) = Just recurse <@> subdir
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go (Closed { maybeFilePath = Just f }) = add <@> f
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go (MovedIn { isDirectory = False, filePath = f }) = add <@> f
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go (MovedOut { isDirectory = False, filePath = f }) = del <@> f
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go (Deleted { isDirectory = False, filePath = f }) = del <@> f
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go _ = noop
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Just a <@> f = a $ dir </> f
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Nothing <@> _ = noop
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{- Pauses the main thread, letting children run until program termination. -}
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waitForTermination :: IO ()
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waitForTermination = do
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mv <- newEmptyMVar
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check softwareTermination mv
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whenM (queryTerminal stdInput) $
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check keyboardSignal mv
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takeMVar mv
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where
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check sig mv = void $
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installHandler sig (CatchOnce $ putMVar mv ()) Nothing
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