340 lines
10 KiB
Haskell
340 lines
10 KiB
Haskell
{- git-annex assistant tree watcher
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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 DeriveDataTypeable, CPP #-}
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module Assistant.Threads.Watcher (
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watchThread,
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WatcherException(..),
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checkCanWatch,
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needLsof,
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onAddSymlink,
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runHandler,
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) where
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import Assistant.Common
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import Assistant.DaemonStatus
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import Assistant.Changes
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import Assistant.Types.Changes
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import Assistant.Alert
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import Utility.DirWatcher
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import Utility.DirWatcher.Types
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import Utility.Lsof
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import qualified Annex
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import qualified Annex.Queue
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import qualified Git
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import qualified Git.UpdateIndex
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import qualified Git.LsFiles as LsFiles
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import qualified Backend
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import Annex.Direct
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import Annex.Content.Direct
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import Annex.CatFile
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import Annex.Link
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import Annex.FileMatcher
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import Annex.ReplaceFile
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import Git.Types
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import Config
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import Utility.ThreadScheduler
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import Data.Bits.Utils
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import Data.Typeable
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import qualified Data.ByteString.Lazy as L
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import qualified Control.Exception as E
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import Data.Time.Clock
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checkCanWatch :: Annex ()
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checkCanWatch
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| canWatch = do
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liftIO setupLsof
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unlessM (liftIO (inPath "lsof") <||> Annex.getState Annex.force)
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needLsof
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| otherwise = error "watch mode is not available on this system"
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needLsof :: Annex ()
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needLsof = error $ unlines
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[ "The lsof command is needed for watch mode to be safe, and is not in PATH."
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, "To override lsof checks to ensure that files are not open for writing"
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, "when added to the annex, you can use --force"
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, "Be warned: This can corrupt data in the annex, and make fsck complain."
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]
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{- A special exception that can be thrown to pause or resume the watcher. -}
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data WatcherException = PauseWatcher | ResumeWatcher
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deriving (Show, Eq, Typeable)
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instance E.Exception WatcherException
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watchThread :: NamedThread
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watchThread = namedThread "Watcher" $
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ifM (liftAnnex $ annexAutoCommit <$> Annex.getGitConfig)
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( runWatcher
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, waitFor ResumeWatcher runWatcher
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)
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runWatcher :: Assistant ()
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runWatcher = do
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startup <- asIO1 startupScan
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matcher <- liftAnnex $ largeFilesMatcher
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direct <- liftAnnex isDirect
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symlinkssupported <- liftAnnex $ coreSymlinks <$> Annex.getGitConfig
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addhook <- hook $ if direct
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then onAddDirect symlinkssupported matcher
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else onAdd matcher
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delhook <- hook onDel
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addsymlinkhook <- hook $ onAddSymlink direct
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deldirhook <- hook onDelDir
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errhook <- hook onErr
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let hooks = mkWatchHooks
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{ addHook = addhook
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, delHook = delhook
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, addSymlinkHook = addsymlinkhook
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, delDirHook = deldirhook
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, errHook = errhook
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}
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handle <- liftIO $ watchDir "." ignored hooks startup
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debug [ "watching", "."]
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{- Let the DirWatcher thread run until signalled to pause it,
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- then wait for a resume signal, and restart. -}
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waitFor PauseWatcher $ do
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liftIO $ stopWatchDir handle
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waitFor ResumeWatcher runWatcher
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where
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hook a = Just <$> asIO2 (runHandler a)
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waitFor :: WatcherException -> Assistant () -> Assistant ()
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waitFor sig next = do
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r <- liftIO $ (E.try pause :: IO (Either E.SomeException ()))
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case r of
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Left e -> case E.fromException e of
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Just s
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| s == sig -> next
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_ -> noop
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_ -> noop
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where
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pause = runEvery (Seconds 86400) noop
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{- Initial scartup scan. The action should return once the scan is complete. -}
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startupScan :: IO a -> Assistant a
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startupScan scanner = do
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liftAnnex $ showAction "scanning"
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alertWhile' startupScanAlert $ do
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r <- liftIO $ scanner
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-- Notice any files that were deleted before
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-- watching was started.
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top <- liftAnnex $ fromRepo Git.repoPath
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(fs, cleanup) <- liftAnnex $ inRepo $ LsFiles.deleted [top]
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forM_ fs $ \f -> do
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liftAnnex $ onDel' f
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maybe noop recordChange =<< madeChange f RmChange
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void $ liftIO $ cleanup
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liftAnnex $ showAction "started"
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liftIO $ putStrLn ""
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modifyDaemonStatus_ $ \s -> s { scanComplete = True }
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return (True, r)
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ignored :: FilePath -> Bool
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ignored = ig . takeFileName
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where
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ig ".git" = True
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ig ".gitignore" = True
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ig ".gitattributes" = True
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#ifdef darwin_HOST_OS
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ig ".DS_Store" = True
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#endif
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ig _ = False
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type Handler = FilePath -> Maybe FileStatus -> Assistant (Maybe Change)
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{- Runs an action handler, and if there was a change, adds it to the ChangeChan.
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-
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- Exceptions are ignored, otherwise a whole watcher thread could be crashed.
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-}
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runHandler :: Handler -> FilePath -> Maybe FileStatus -> Assistant ()
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runHandler handler file filestatus = void $ do
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r <- tryIO <~> handler (normalize file) filestatus
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case r of
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Left e -> liftIO $ print e
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Right Nothing -> noop
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Right (Just change) -> do
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-- Just in case the commit thread is not
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-- flushing the queue fast enough.
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liftAnnex $ Annex.Queue.flushWhenFull
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recordChange change
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where
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normalize f
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| "./" `isPrefixOf` file = drop 2 f
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| otherwise = f
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{- Small files are added to git as-is, while large ones go into the annex. -}
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add :: FileMatcher -> FilePath -> Assistant (Maybe Change)
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add bigfilematcher file = ifM (liftAnnex $ checkFileMatcher bigfilematcher file)
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( pendingAddChange file
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, do
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liftAnnex $ Annex.Queue.addCommand "add"
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[Params "--force --"] [file]
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madeChange file AddFileChange
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)
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onAdd :: FileMatcher -> Handler
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onAdd matcher file filestatus
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| maybe False isRegularFile filestatus = add matcher file
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| otherwise = noChange
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{- In direct mode, add events are received for both new files, and
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- modified existing files.
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-}
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onAddDirect :: Bool -> FileMatcher -> Handler
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onAddDirect symlinkssupported matcher file fs = do
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v <- liftAnnex $ catKeyFile file
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case (v, fs) of
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(Just key, Just filestatus) ->
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ifM (liftAnnex $ sameFileStatus key filestatus)
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{- It's possible to get an add event for
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- an existing file that is not
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- really modified, but it might have
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- just been deleted and been put back,
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- so it symlink is restaged to make sure. -}
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( ifM (scanComplete <$> getDaemonStatus)
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( do
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link <- liftAnnex $ inRepo $ gitAnnexLink file key
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addLink file link (Just key)
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, noChange
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)
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, guardSymlinkStandin (Just key) $ do
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debug ["changed direct", file]
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liftAnnex $ changedDirect key file
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add matcher file
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)
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_ -> guardSymlinkStandin Nothing $ do
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debug ["add direct", file]
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add matcher file
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where
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{- On a filesystem without symlinks, we'll get changes for regular
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- files that git uses to stand-in for symlinks. Detect when
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- this happens, and stage the symlink, rather than annexing the
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- file. -}
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guardSymlinkStandin mk a
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| symlinkssupported = a
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| otherwise = do
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linktarget <- liftAnnex $ getAnnexLinkTarget file
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case linktarget of
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Nothing -> a
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Just lt -> do
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case fileKey $ takeFileName lt of
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Nothing -> noop
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Just key -> void $ liftAnnex $
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addAssociatedFile key file
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onAddSymlink' linktarget mk True file fs
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{- A symlink might be an arbitrary symlink, which is just added.
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- Or, if it is a git-annex symlink, ensure it points to the content
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- before adding it.
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-}
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onAddSymlink :: Bool -> Handler
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onAddSymlink isdirect file filestatus = do
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linktarget <- liftIO (catchMaybeIO $ readSymbolicLink file)
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kv <- liftAnnex (Backend.lookupFile file)
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onAddSymlink' linktarget (fmap fst kv) isdirect file filestatus
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onAddSymlink' :: Maybe String -> Maybe Key -> Bool -> Handler
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onAddSymlink' linktarget mk isdirect file filestatus = go mk
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where
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go (Just key) = do
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when isdirect $
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liftAnnex $ void $ addAssociatedFile key file
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link <- liftAnnex $ inRepo $ gitAnnexLink file key
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if linktarget == Just link
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then ensurestaged (Just link) =<< getDaemonStatus
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else do
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unless isdirect $
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liftAnnex $ replaceFile file $
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makeAnnexLink link
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addLink file link (Just key)
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-- other symlink, not git-annex
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go Nothing = ensurestaged linktarget =<< getDaemonStatus
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{- This is often called on symlinks that are already
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- staged correctly. A symlink may have been deleted
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- and being re-added, or added when the watcher was
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- not running. So they're normally restaged to make sure.
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-
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- As an optimisation, during the startup scan, avoid
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- restaging everything. Only links that were created since
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- the last time the daemon was running are staged.
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- (If the daemon has never ran before, avoid staging
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- links too.)
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-}
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ensurestaged (Just link) daemonstatus
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| scanComplete daemonstatus = addLink file link mk
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| otherwise = case filestatus of
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Just s
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| not (afterLastDaemonRun (statusChangeTime s) daemonstatus) -> noChange
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_ -> addLink file link mk
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ensurestaged Nothing _ = noChange
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{- For speed, tries to reuse the existing blob for symlink target. -}
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addLink :: FilePath -> FilePath -> Maybe Key -> Assistant (Maybe Change)
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addLink file link mk = do
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debug ["add symlink", file]
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liftAnnex $ do
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v <- catObjectDetails $ Ref $ ':':file
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case v of
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Just (currlink, sha)
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| s2w8 link == L.unpack currlink ->
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stageSymlink file sha
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_ -> stageSymlink file =<< hashSymlink link
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madeChange file $ LinkChange mk
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onDel :: Handler
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onDel file _ = do
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debug ["file deleted", file]
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liftAnnex $ onDel' file
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madeChange file RmChange
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onDel' :: FilePath -> Annex ()
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onDel' file = do
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whenM isDirect $ do
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mkey <- catKeyFile file
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case mkey of
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Nothing -> noop
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Just key -> void $ removeAssociatedFile key file
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Annex.Queue.addUpdateIndex =<<
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inRepo (Git.UpdateIndex.unstageFile file)
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{- A directory has been deleted, or moved, so tell git to remove anything
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- that was inside it from its cache. Since it could reappear at any time,
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- use --cached to only delete it from the index.
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-
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- This queues up a lot of RmChanges, which assists the Committer in
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- pairing up renamed files when the directory was renamed. -}
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onDelDir :: Handler
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onDelDir dir _ = do
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debug ["directory deleted", dir]
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(fs, clean) <- liftAnnex $ inRepo $ LsFiles.deleted [dir]
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liftAnnex $ mapM_ onDel' fs
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-- Get the events queued up as fast as possible, so the
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-- committer sees them all in one block.
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now <- liftIO getCurrentTime
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recordChanges $ map (\f -> Change now f RmChange) fs
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void $ liftIO $ clean
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liftAnnex $ Annex.Queue.flushWhenFull
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noChange
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{- Called when there's an error with inotify or kqueue. -}
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onErr :: Handler
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onErr msg _ = do
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liftAnnex $ warning msg
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void $ addAlert $ warningAlert "watcher" msg
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noChange
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