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