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{- generic directory watching interface
-
- Uses either inotify or kqueue to watch a directory (and subdirectories)
- for changes, and runs hooks for different sorts of events as they occur.
-
- Copyright 2012 Joey Hess <joey@kitenet.net>
-
- Licensed under the GNU GPL version 3 or higher.
-}
{-# LANGUAGE CPP #-}
module Utility.DirWatcher where
import Utility.Types.DirWatcher
#if WITH_INOTIFY
import qualified Utility.INotify as INotify
import qualified System.INotify as INotify
#endif
#if WITH_KQUEUE
import qualified Utility.Kqueue as Kqueue
import Control.Concurrent
#endif
type Pruner = FilePath -> Bool
canWatch :: Bool
#if (WITH_INOTIFY || WITH_KQUEUE)
canWatch = True
#else
#if defined linux_HOST_OS
#warning "Building without inotify support"
#endif
canWatch = False
#endif
/* With inotify, discrete events will be received when making multiple changes
* to the same filename. For example, adding it, deleting it, and adding it
* again will be three events.
*
* OTOH, with kqueue, often only one event is received, indicating the most
* recent state of the file.
*/
eventsCoalesce :: Bool
#if WITH_INOTIFY
eventsCoalesce = False
#else
#if WITH_KQUEUE
eventsCoalesce = True
#else
eventsCoalesce = undefined
#endif
#endif
/* With inotify, file closing is tracked to some extent, so an add event
* will always be received for a file once its writer closes it, and
* (typically) not before. This may mean multiple add events for the same file.
*
* OTOH, with kqueue, add events will often be received while a file is
* still being written to, and then no add event will be received once the
* writer closes it.
*/
closingTracked :: Bool
#if WITH_INOTIFY
closingTracked = True
#else
#if WITH_KQUEUE
closingTracked = False
#else
closingTracked = undefined
#endif
#endif
/* With inotify, modifications to existing files can be tracked.
* Kqueue does not support this.
*/
modifyTracked :: Bool
#if WITH_INOTIFY
modifyTracked = True
#else
#if WITH_KQUEUE
modifyTracked = False
#else
modifyTracked = undefined
#endif
#endif
/* Starts a watcher thread. The runStartup action is passed a scanner action
* to run, that will return once the initial directory scan is complete.
* Once runStartup returns, the watcher thread continues running,
* and processing events. Returns a DirWatcherHandle that can be used
* to shutdown later. */
#if WITH_INOTIFY
type DirWatcherHandle = INotify.INotify
watchDir :: FilePath -> Pruner -> WatchHooks -> (IO () -> IO ()) -> IO DirWatcherHandle
watchDir dir prune hooks runstartup = do
i <- INotify.initINotify
runstartup $ INotify.watchDir i dir prune hooks
return i
#else
#if WITH_KQUEUE
type DirWatcherHandle = ThreadId
watchDir :: FilePath -> Pruner -> WatchHooks -> (IO Kqueue.Kqueue -> IO Kqueue.Kqueue) -> IO DirWatcherHandle
watchDir dir prune hooks runstartup = do
kq <- runstartup $ Kqueue.initKqueue dir prune
forkIO $ Kqueue.runHooks kq hooks
#else
type DirWatcherHandle = ()
watchDir :: FilePath -> Pruner -> WatchHooks -> (IO () -> IO ()) -> IO DirWatcherHandle
watchDir = undefined
#endif
#endif
#if WITH_INOTIFY
stopWatchDir :: DirWatcherHandle -> IO ()
stopWatchDir = INotify.killINotify
#else
#if WITH_KQUEUE
stopWatchDir :: DirWatcherHandle -> IO ()
stopWatchDir = killThread
#else
stopWatchDir :: DirWatcherHandle -> IO ()
stopWatchDir = undefined
#endif
#endif
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