183 lines
6.6 KiB
Haskell
183 lines
6.6 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 2011-2021 Joey Hess <id@joeyh.name>
|
|
-
|
|
- Licensed under the GNU AGPL version 3 or higher.
|
|
-}
|
|
|
|
{-# LANGUAGE OverloadedStrings #-}
|
|
|
|
module Annex.Journal where
|
|
|
|
import Annex.Common
|
|
import qualified Git
|
|
import Annex.Perms
|
|
import Annex.Tmp
|
|
import Annex.LockFile
|
|
import Utility.Directory.Stream
|
|
|
|
import qualified Data.ByteString.Lazy as L
|
|
import qualified Data.ByteString as S
|
|
import qualified System.FilePath.ByteString as P
|
|
import Data.ByteString.Builder
|
|
import Data.Char
|
|
|
|
class Journalable t where
|
|
writeJournalHandle :: Handle -> t -> IO ()
|
|
journalableByteString :: t -> L.ByteString
|
|
|
|
instance Journalable L.ByteString where
|
|
writeJournalHandle = L.hPut
|
|
journalableByteString = id
|
|
|
|
-- This is more efficient than the ByteString instance.
|
|
instance Journalable Builder where
|
|
writeJournalHandle = hPutBuilder
|
|
journalableByteString = toLazyByteString
|
|
|
|
{- When a file in the git-annex branch is changed, this indicates what
|
|
- repository UUID (or in some cases, UUIDs) a change is regarding.
|
|
-
|
|
- Using this lets changes regarding private UUIDs be written to the
|
|
- private index, rather than to the main branch index, so it does
|
|
- not get exposed to other remotes.
|
|
-}
|
|
data RegardingUUID = RegardingUUID [UUID]
|
|
|
|
regardingPrivateUUID :: RegardingUUID -> Bool
|
|
regardingPrivateUUID (RegardingUUID []) = False
|
|
regardingPrivateUUID (RegardingUUID _) = True -- TODO
|
|
|
|
-- Are any private UUIDs known to exist? If so, extra work has to be done,
|
|
-- to check for information separately recorded for them, outside the usual
|
|
-- locations.
|
|
privateUUIDsKnown :: Bool
|
|
privateUUIDsKnown = True -- TODO
|
|
|
|
{- 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 :: Journalable content => JournalLocked -> RegardingUUID -> RawFilePath -> content -> Annex ()
|
|
setJournalFile _jl ru file content = withOtherTmp $ \tmp -> do
|
|
jd <- fromRepo $ if regardingPrivateUUID ru
|
|
then gitAnnexPrivateJournalDir
|
|
else gitAnnexJournalDir
|
|
createAnnexDirectory jd
|
|
-- journal file is written atomically
|
|
let jfile = journalFile file
|
|
let tmpfile = fromRawFilePath (tmp P.</> jfile)
|
|
liftIO $ do
|
|
withFile tmpfile WriteMode $ \h -> writeJournalHandle h content
|
|
moveFile tmpfile (fromRawFilePath (jd P.</> jfile))
|
|
|
|
{- Gets any journalled content for a file in the branch. -}
|
|
getJournalFile :: JournalLocked -> GetPrivate -> RawFilePath -> Annex (Maybe L.ByteString)
|
|
getJournalFile _jl = getJournalFileStale
|
|
|
|
data GetPrivate = GetPrivate Bool
|
|
|
|
{- 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.
|
|
-
|
|
- The file is read strictly so that its content can safely be fed into
|
|
- an operation that modifies the file. While setJournalFile doesn't
|
|
- write directly to journal files and so probably avoids problems with
|
|
- writing to the same file that's being read, but there could be
|
|
- concurrency or other issues with a lazy read, and the minor loss of
|
|
- laziness doesn't matter much, as the files are not very large.
|
|
-}
|
|
getJournalFileStale :: GetPrivate -> RawFilePath -> Annex (Maybe L.ByteString)
|
|
getJournalFileStale (GetPrivate getprivate) file = inRepo $ \g ->
|
|
if getprivate && privateUUIDsKnown
|
|
then do
|
|
x <- getfrom (gitAnnexJournalDir g)
|
|
y <- getfrom (gitAnnexPrivateJournalDir g)
|
|
-- This concacenation is the same as happens in a
|
|
-- merge of two git-annex branches.
|
|
return (x <> y)
|
|
else getfrom (gitAnnexJournalDir g)
|
|
where
|
|
jfile = journalFile file
|
|
getfrom d = catchMaybeIO $
|
|
L.fromStrict <$> S.readFile (fromRawFilePath (d P.</> jfile))
|
|
|
|
{- List of existing journal files in a journal directory, but without locking,
|
|
- may miss new ones just being added, or may have false positives if the
|
|
- journal is staged as it is run. -}
|
|
getJournalledFilesStale :: (Git.Repo -> RawFilePath) -> Annex [RawFilePath]
|
|
getJournalledFilesStale getjournaldir = do
|
|
g <- gitRepo
|
|
fs <- liftIO $ catchDefaultIO [] $
|
|
getDirectoryContents $ fromRawFilePath (getjournaldir g)
|
|
return $ filter (`notElem` [".", ".."]) $
|
|
map (fileJournal . toRawFilePath) fs
|
|
|
|
{- Directory handle open on a journal directory. -}
|
|
withJournalHandle :: (Git.Repo -> RawFilePath) -> (DirectoryHandle -> IO a) -> Annex a
|
|
withJournalHandle getjournaldir a = do
|
|
d <- fromRawFilePath <$> fromRepo getjournaldir
|
|
bracketIO (openDirectory d) closeDirectory (liftIO . a)
|
|
|
|
{- Checks if there are changes in the journal. -}
|
|
journalDirty :: (Git.Repo -> RawFilePath) -> Annex Bool
|
|
journalDirty getjournaldir = do
|
|
d <- fromRawFilePath <$> fromRepo getjournaldir
|
|
liftIO $
|
|
(not <$> isDirectoryEmpty d)
|
|
`catchIO` (const $ doesDirectoryExist d)
|
|
|
|
{- Produces a filename to use in the journal for a file on the branch.
|
|
- The filename does not include the journal directory.
|
|
-
|
|
- 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 :: RawFilePath -> RawFilePath
|
|
journalFile file = S.concatMap mangle file
|
|
where
|
|
mangle c
|
|
| P.isPathSeparator c = S.singleton underscore
|
|
| c == underscore = S.pack [underscore, underscore]
|
|
| otherwise = S.singleton c
|
|
underscore = fromIntegral (ord '_')
|
|
|
|
{- Converts a journal file (relative to the journal dir) back to the
|
|
- filename on the branch. -}
|
|
fileJournal :: RawFilePath -> RawFilePath
|
|
fileJournal = go
|
|
where
|
|
go b =
|
|
let (h, t) = S.break (== underscore) b
|
|
in h <> case S.uncons t of
|
|
Nothing -> t
|
|
Just (_u, t') -> case S.uncons t' of
|
|
Nothing -> t'
|
|
Just (w, t'')
|
|
| w == underscore ->
|
|
S.cons underscore (go t'')
|
|
| otherwise ->
|
|
S.cons P.pathSeparator (go t')
|
|
|
|
underscore = fromIntegral (ord '_')
|
|
|
|
{- 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
|