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|
{- git-annex assistant tree watcher
-
- Copyright 2012 Joey Hess <joey@kitenet.net>
-
- Licensed under the GNU GPL version 3 or higher.
-}
{-# LANGUAGE DeriveDataTypeable, CPP #-}
module Assistant.Threads.Watcher (
watchThread,
WatcherException(..),
checkCanWatch,
needLsof,
onAddSymlink,
runHandler,
) where
import Assistant.Common
import Assistant.DaemonStatus
import Assistant.Changes
import Assistant.Types.Changes
import Assistant.Alert
import Utility.DirWatcher
import Utility.DirWatcher.Types
import Utility.Lsof
import qualified Annex
import qualified Annex.Queue
import qualified Git
import qualified Git.UpdateIndex
import qualified Git.LsFiles as LsFiles
import qualified Backend
import Annex.Content
import Annex.Direct
import Annex.Content.Direct
import Annex.CatFile
import Annex.Link
import Annex.FileMatcher
import Git.Types
import Config
import Utility.ThreadScheduler
import Data.Bits.Utils
import Data.Typeable
import qualified Data.ByteString.Lazy as L
import qualified Control.Exception as E
import Data.Time.Clock
checkCanWatch :: Annex ()
checkCanWatch
| canWatch = do
liftIO setupLsof
unlessM (liftIO (inPath "lsof") <||> Annex.getState Annex.force)
needLsof
| otherwise = error "watch mode is not available on this system"
needLsof :: Annex ()
needLsof = error $ unlines
[ "The lsof command is needed for watch mode to be safe, and is not in PATH."
, "To override lsof checks to ensure that files are not open for writing"
, "when added to the annex, you can use --force"
, "Be warned: This can corrupt data in the annex, and make fsck complain."
]
{- A special exception that can be thrown to pause or resume the watcher. -}
data WatcherException = PauseWatcher | ResumeWatcher
deriving (Show, Eq, Typeable)
instance E.Exception WatcherException
watchThread :: NamedThread
watchThread = namedThread "Watcher" $
ifM (liftAnnex $ annexAutoCommit <$> Annex.getGitConfig)
( runWatcher
, waitFor ResumeWatcher runWatcher
)
runWatcher :: Assistant ()
runWatcher = do
startup <- asIO1 startupScan
matcher <- liftAnnex $ largeFilesMatcher
direct <- liftAnnex isDirect
addhook <- hook $ if direct then onAddDirect matcher else onAdd matcher
delhook <- hook onDel
addsymlinkhook <- hook $ onAddSymlink direct
deldirhook <- hook onDelDir
errhook <- hook onErr
let hooks = mkWatchHooks
{ addHook = addhook
, delHook = delhook
, addSymlinkHook = addsymlinkhook
, delDirHook = deldirhook
, errHook = errhook
}
handle <- liftIO $ watchDir "." ignored hooks startup
debug [ "watching", "."]
{- Let the DirWatcher thread run until signalled to pause it,
- then wait for a resume signal, and restart. -}
waitFor PauseWatcher $ do
liftIO $ stopWatchDir handle
waitFor ResumeWatcher runWatcher
where
hook a = Just <$> asIO2 (runHandler a)
waitFor :: WatcherException -> Assistant () -> Assistant ()
waitFor sig next = do
r <- liftIO $ (E.try pause :: IO (Either E.SomeException ()))
case r of
Left e -> case E.fromException e of
Just s
| s == sig -> next
_ -> noop
_ -> noop
where
pause = runEvery (Seconds 86400) noop
{- Initial scartup scan. The action should return once the scan is complete. -}
startupScan :: IO a -> Assistant a
startupScan scanner = do
liftAnnex $ showAction "scanning"
alertWhile' startupScanAlert $ do
r <- liftIO $ scanner
-- Notice any files that were deleted before
-- watching was started.
top <- liftAnnex $ fromRepo Git.repoPath
(fs, cleanup) <- liftAnnex $ inRepo $ LsFiles.deleted [top]
forM_ fs $ \f -> do
liftAnnex $ Annex.Queue.addUpdateIndex =<<
inRepo (Git.UpdateIndex.unstageFile f)
maybe noop recordChange =<< madeChange f RmChange
void $ liftIO $ cleanup
liftAnnex $ showAction "started"
liftIO $ putStrLn ""
modifyDaemonStatus_ $ \s -> s { scanComplete = True }
return (True, r)
ignored :: FilePath -> Bool
ignored = ig . takeFileName
where
ig ".git" = True
ig ".gitignore" = True
ig ".gitattributes" = True
#ifdef darwin_HOST_OS
ig ".DS_Store" = True
#endif
ig _ = False
type Handler = FilePath -> Maybe FileStatus -> Assistant (Maybe Change)
{- Runs an action handler, and if there was a change, adds it to the ChangeChan.
-
- Exceptions are ignored, otherwise a whole watcher thread could be crashed.
-}
runHandler :: Handler -> FilePath -> Maybe FileStatus -> Assistant ()
runHandler handler file filestatus = void $ do
r <- tryIO <~> handler file filestatus
case r of
Left e -> liftIO $ print e
Right Nothing -> noop
Right (Just change) -> do
-- Just in case the commit thread is not
-- flushing the queue fast enough.
liftAnnex $ Annex.Queue.flushWhenFull
recordChange change
{- Small files are added to git as-is, while large ones go into the annex. -}
add :: FileMatcher -> FilePath -> Assistant (Maybe Change)
add bigfilematcher file = ifM (liftAnnex $ checkFileMatcher bigfilematcher file)
( pendingAddChange file
, do
liftAnnex $ Annex.Queue.addCommand "add"
[Params "--force --"] [file]
madeChange file AddFileChange
)
onAdd :: FileMatcher -> Handler
onAdd matcher file filestatus
| maybe False isRegularFile filestatus = add matcher file
| otherwise = noChange
{- In direct mode, add events are received for both new files, and
- modified existing files. -}
onAddDirect :: FileMatcher -> Handler
onAddDirect matcher file fs = do
v <- liftAnnex $ catKeyFile file
case (v, fs) of
(Just key, Just filestatus) ->
ifM (liftAnnex $ sameFileStatus key filestatus)
{- It's possible to get an add event for
- an existing file that is not
- really modified, but it might have
- just been deleted and been put back,
- so it symlink is restaged to make sure. -}
( do
link <- liftAnnex $ calcGitLink file key
addLink file link (Just key)
, do
debug ["changed direct", file]
liftAnnex $ changedDirect key file
add matcher file
)
_ -> do
debug ["add direct", file]
add matcher file
{- A symlink might be an arbitrary symlink, which is just added.
- Or, if it is a git-annex symlink, ensure it points to the content
- before adding it.
-}
onAddSymlink :: Bool -> Handler
onAddSymlink isdirect file filestatus = go =<< liftAnnex (Backend.lookupFile file)
where
go (Just (key, _)) = do
when isdirect $
liftAnnex $ void $ addAssociatedFile key file
link <- liftAnnex $ calcGitLink file key
ifM ((==) (Just link) <$> liftIO (catchMaybeIO $ readSymbolicLink file))
( ensurestaged (Just link) (Just key) =<< getDaemonStatus
, do
unless isdirect $ do
liftIO $ removeFile file
liftAnnex $ Backend.makeAnnexLink link file
addLink file link (Just key)
)
go Nothing = do -- other symlink
mlink <- liftIO (catchMaybeIO $ readSymbolicLink file)
ensurestaged mlink Nothing =<< getDaemonStatus
{- This is often called on symlinks that are already
- staged correctly. A symlink may have been deleted
- and being re-added, or added when the watcher was
- not running. So they're normally restaged to make sure.
-
- As an optimisation, during the startup scan, avoid
- restaging everything. Only links that were created since
- the last time the daemon was running are staged.
- (If the daemon has never ran before, avoid staging
- links too.)
-}
ensurestaged (Just link) mk daemonstatus
| scanComplete daemonstatus = addLink file link mk
| otherwise = case filestatus of
Just s
| not (afterLastDaemonRun (statusChangeTime s) daemonstatus) -> noChange
_ -> addLink file link mk
ensurestaged Nothing _ _ = noChange
{- For speed, tries to reuse the existing blob for symlink target. -}
addLink :: FilePath -> FilePath -> Maybe Key -> Assistant (Maybe Change)
addLink file link mk = do
debug ["add symlink", file]
liftAnnex $ do
v <- catObjectDetails $ Ref $ ':':file
case v of
Just (currlink, sha)
| s2w8 link == L.unpack currlink ->
stageSymlink file sha
_ -> stageSymlink file =<< hashSymlink link
madeChange file $ LinkChange mk
onDel :: Handler
onDel file _ = do
debug ["file deleted", file]
liftAnnex $
Annex.Queue.addUpdateIndex =<<
inRepo (Git.UpdateIndex.unstageFile file)
madeChange file RmChange
{- A directory has been deleted, or moved, so tell git to remove anything
- that was inside it from its cache. Since it could reappear at any time,
- use --cached to only delete it from the index.
-
- This queues up a lot of RmChanges, which assists the Committer in
- pairing up renamed files when the directory was renamed. -}
onDelDir :: Handler
onDelDir dir _ = do
debug ["directory deleted", dir]
(fs, clean) <- liftAnnex $ inRepo $ LsFiles.deleted [dir]
liftAnnex $ forM_ fs $ \f -> Annex.Queue.addUpdateIndex =<<
inRepo (Git.UpdateIndex.unstageFile f)
-- Get the events queued up as fast as possible, so the
-- committer sees them all in one block.
now <- liftIO getCurrentTime
forM_ fs $ \f -> recordChange $ Change now f RmChange
void $ liftIO $ clean
liftAnnex $ Annex.Queue.flushWhenFull
noChange
{- Called when there's an error with inotify or kqueue. -}
onErr :: Handler
onErr msg _ = do
liftAnnex $ warning msg
void $ addAlert $ warningAlert "watcher" msg
noChange
|