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{- git-annex inode sentinal file
-
- Copyright 2012-2015 Joey Hess <id@joeyh.name>
-
- Licensed under the GNU GPL version 3 or higher.
-}
{-# LANGUAGE CPP #-}
module Annex.InodeSentinal where
import Annex.Common
import qualified Annex
import Utility.InodeCache
import Annex.Perms
{- If the sendinal shows the inodes have changed, only the size and mtime
- are compared. -}
compareInodeCaches :: InodeCache -> InodeCache -> Annex Bool
compareInodeCaches x y
| compareStrong x y = return True
| otherwise = ifM inodesChanged
( return $ compareWeak x y
, return False
)
compareInodeCachesWith :: Annex InodeComparisonType
compareInodeCachesWith = ifM inodesChanged ( return Weakly, return Strongly )
{- Checks if one of the provided old InodeCache matches the current
- version of a file. -}
sameInodeCache :: FilePath -> [InodeCache] -> Annex Bool
sameInodeCache _ [] = return False
sameInodeCache file old = go =<< withTSDelta (liftIO . genInodeCache file)
where
go Nothing = return False
go (Just curr) = elemInodeCaches curr old
elemInodeCaches :: InodeCache -> [InodeCache] -> Annex Bool
elemInodeCaches _ [] = return False
elemInodeCaches c (l:ls) = ifM (compareInodeCaches c l)
( return True
, elemInodeCaches c ls
)
{- Some filesystems get new inodes each time they are mounted.
- In order to work on such a filesystem, a sentinal file is used to detect
- when the inodes have changed.
-
- If the sentinal file does not exist, we have to assume that the
- inodes have changed.
-}
inodesChanged :: Annex Bool
inodesChanged = sentinalInodesChanged <$> sentinalStatus
withTSDelta :: (TSDelta -> Annex a) -> Annex a
withTSDelta a = a =<< getTSDelta
getTSDelta :: Annex TSDelta
#ifdef mingw32_HOST_OS
getTSDelta = sentinalTSDelta <$> sentinalStatus
#else
getTSDelta = pure noTSDelta -- optimisation
#endif
sentinalStatus :: Annex SentinalStatus
sentinalStatus = maybe check return =<< Annex.getState Annex.sentinalstatus
where
check = do
sc <- liftIO . checkSentinalFile =<< annexSentinalFile
Annex.changeState $ \s -> s { Annex.sentinalstatus = Just sc }
return sc
{- The sentinal file is only created when first initializing a repository.
- If there are any annexed objects in the repository already, creating
- the file would invalidate their inode caches. -}
createInodeSentinalFile :: Bool -> Annex ()
createInodeSentinalFile evenwithobjects =
unlessM (alreadyexists <||> hasobjects) $ do
s <- annexSentinalFile
createAnnexDirectory (parentDir (sentinalFile s))
liftIO $ writeSentinalFile s
where
alreadyexists = liftIO. sentinalFileExists =<< annexSentinalFile
hasobjects
| evenwithobjects = pure False
| otherwise = liftIO . doesDirectoryExist =<< fromRepo gitAnnexObjectDir
annexSentinalFile :: Annex SentinalFile
annexSentinalFile = do
sentinalfile <- fromRepo gitAnnexInodeSentinal
sentinalcachefile <- fromRepo gitAnnexInodeSentinalCache
return SentinalFile
{ sentinalFile = sentinalfile
, sentinalCacheFile = sentinalcachefile
}
|
