git-annex/Annex/Journal.hs
Joey Hess c784ef4586 unify exception handling into Utility.Exception
Removed old extensible-exceptions, only needed for very old ghc.

Made webdav use Utility.Exception, to work after some changes in DAV's
exception handling.

Removed Annex.Exception. Mostly this was trivial, but note that
tryAnnex is replaced with tryNonAsync and catchAnnex replaced with
catchNonAsync. In theory that could be a behavior change, since the former
caught all exceptions, and the latter don't catch async exceptions.

However, in practice, nothing in the Annex monad uses async exceptions.
Grepping for throwTo and killThread only find stuff in the assistant,
which does not seem related.

Command.Add.undo is changed to accept a SomeException, and things
that use it for rollback now catch non-async exceptions, rather than
only IOExceptions.
2014-08-07 22:03:29 -04:00

120 lines
4.1 KiB
Haskell

{- management of the git-annex journal
-
- The journal is used to queue up changes before they are committed to the
- git-annex branch. Among other things, it ensures that if git-annex is
- interrupted, its recorded data is not lost.
-
- Copyright 2011-2013 Joey Hess <joey@kitenet.net>
-
- Licensed under the GNU GPL version 3 or higher.
-}
{-# LANGUAGE CPP #-}
module Annex.Journal where
import Common.Annex
import qualified Git
import Annex.Perms
import Annex.LockFile
{- Records content for a file in the branch to the journal.
-
- Using the journal, rather than immediatly staging content to the index
- avoids git needing to rewrite the index after every change.
-
- The file in the journal is updated atomically, which allows
- getJournalFileStale to always return a consistent journal file
- content, although possibly not the most current one.
-}
setJournalFile :: JournalLocked -> FilePath -> String -> Annex ()
setJournalFile _jl file content = do
tmp <- fromRepo gitAnnexTmpMiscDir
createAnnexDirectory =<< fromRepo gitAnnexJournalDir
createAnnexDirectory tmp
-- journal file is written atomically
jfile <- fromRepo $ journalFile file
let tmpfile = tmp </> takeFileName jfile
liftIO $ do
withFile tmpfile WriteMode $ \h -> do
fileEncoding h
#ifdef mingw32_HOST_OS
hSetNewlineMode h noNewlineTranslation
#endif
hPutStr h content
moveFile tmpfile jfile
{- Gets any journalled content for a file in the branch. -}
getJournalFile :: JournalLocked -> FilePath -> Annex (Maybe String)
getJournalFile _jl = getJournalFileStale
{- Without locking, this is not guaranteed to be the most recent
- version of the file in the journal, so should not be used as a basis for
- changes. -}
getJournalFileStale :: FilePath -> Annex (Maybe String)
getJournalFileStale file = inRepo $ \g -> catchMaybeIO $
readFileStrictAnyEncoding $ journalFile file g
{- List of files that have updated content in the journal. -}
getJournalledFiles :: JournalLocked -> Annex [FilePath]
getJournalledFiles jl = map fileJournal <$> getJournalFiles jl
getJournalledFilesStale :: Annex [FilePath]
getJournalledFilesStale = map fileJournal <$> getJournalFilesStale
{- List of existing journal files. -}
getJournalFiles :: JournalLocked -> Annex [FilePath]
getJournalFiles _jl = getJournalFilesStale
{- List of existing journal files, but without locking, may miss new ones
- just being added, or may have false positives if the journal is staged
- as it is run. -}
getJournalFilesStale :: Annex [FilePath]
getJournalFilesStale = do
g <- gitRepo
fs <- liftIO $ catchDefaultIO [] $
getDirectoryContents $ gitAnnexJournalDir g
return $ filter (`notElem` [".", ".."]) fs
withJournalHandle :: (DirectoryHandle -> IO a) -> Annex a
withJournalHandle a = do
d <- fromRepo gitAnnexJournalDir
bracketIO (openDirectory d) closeDirectory (liftIO . a)
{- Checks if there are changes in the journal. -}
journalDirty :: Annex Bool
journalDirty = do
d <- fromRepo gitAnnexJournalDir
liftIO $
(not <$> isDirectoryEmpty d)
`catchIO` (const $ doesDirectoryExist d)
{- Produces a filename to use in the journal for a file on the branch.
-
- The journal typically won't have a lot of files in it, so the hashing
- used in the branch is not necessary, and all the files are put directly
- in the journal directory.
-}
journalFile :: FilePath -> Git.Repo -> FilePath
journalFile file repo = gitAnnexJournalDir repo </> concatMap mangle file
where
mangle c
| c == pathSeparator = "_"
| c == '_' = "__"
| otherwise = [c]
{- Converts a journal file (relative to the journal dir) back to the
- filename on the branch. -}
fileJournal :: FilePath -> FilePath
fileJournal = replace [pathSeparator, pathSeparator] "_" .
replace "_" [pathSeparator]
{- Sentinal value, only produced by lockJournal; required
- as a parameter by things that need to ensure the journal is
- locked. -}
data JournalLocked = ProduceJournalLocked
{- Runs an action that modifies the journal, using locking to avoid
- contention with other git-annex processes. -}
lockJournal :: (JournalLocked -> Annex a) -> Annex a
lockJournal a = withExclusiveLock gitAnnexJournalLock $ a ProduceJournalLocked