145 lines
4.1 KiB
Haskell
145 lines
4.1 KiB
Haskell
{- generic directory watching interface
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-
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- Uses inotify, or kqueue, or fsevents to watch a directory
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- (and subdirectories) for changes, and runs hooks for different
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- 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.DirWatcher.Types
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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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#if WITH_FSEVENTS
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import qualified Utility.FSEvents as FSEvents
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import qualified System.OSX.FSEvents as FSEvents
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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 || WITH_FSEVENTS)
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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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eventsCoalesce :: Bool
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#if (WITH_INOTIFY || WITH_FSEVENTS)
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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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- fsevents behaves similarly, although different event types are used for
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- creating and modification of the 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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closingTracked :: Bool
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#if (WITH_INOTIFY || WITH_FSEVENTS)
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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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{- With inotify, modifications to existing files can be tracked.
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- Kqueue does not support this.
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- Fsevents generates events when an existing file is reopened and rewritten,
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- but not necessarily when it's opened once and modified repeatedly. -}
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modifyTracked :: Bool
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#if (WITH_INOTIFY || WITH_FSEVENTS)
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modifyTracked = True
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#else
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#if WITH_KQUEUE
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modifyTracked = False
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#else
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modifyTracked = 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 prune hooks runstartup = do
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kq <- runstartup $ Kqueue.initKqueue dir prune
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forkIO $ Kqueue.runHooks kq hooks
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#else
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#if WITH_FSEVENTS
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type DirWatcherHandle = FSEvents.EventStream
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watchDir :: FilePath -> Pruner -> WatchHooks -> (IO FSEvents.EventStream -> IO FSEvents.EventStream) -> IO DirWatcherHandle
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watchDir dir prune hooks runstartup =
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runstartup $ FSEvents.watchDir dir prune 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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#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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#if WITH_FSEVENTS
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stopWatchDir :: DirWatcherHandle -> IO ()
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stopWatchDir = FSEvents.eventStreamDestroy
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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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#endif
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