re-add lock journal before reading journal files

This reverts commit 2e6e9876e3fc420a22eee82eedec54ac3f678878.

This is gonna be needed after all.. The append will only be atomic if
the journal is locked, because the file being appended will have to be
moved out of the way to avoid an old version of git-annex seeing an
incomplete write to it. When git-annex finds that the file is not in the
journal, and checks the append location, locking will be needed to avoid
a race causing it to miss it in the append location too due to it being
moved back to the journal.

diff --git a/Annex/Branch.hs b/Annex/Branch.hs
index 456d9d6619309a0417cf4a35f5eef004744cdeda..41ae4207f73c9071737485848db42f78e51b8523 100644 (file)
--- a/Annex/Branch.hs
+++ b/Annex/Branch.hs
@@ -236,7 +236,7 @@ updateTo' pairs = do
                        else return $ "merging " ++
                                unwords (map Git.Ref.describe branches) ++ 
                                " into " ++ fromRef name
-               localtransitions <- getLocalTransitions
+               localtransitions <- getLocalTransitions jl
                unless (null tomerge) $ do
                        showSideAction merge_desc
                        mapM_ checkBranchDifferences refs
@@ -265,7 +265,7 @@ updateTo' pairs = do
                -- Gather any transitions that are new to either the
                -- local branch or a remote ref, which will need to be
                -- applied on the fly.
-               localts <- getLocalTransitions
+               localts <- lockJournal getLocalTransitions
                remotets <- mapM getRefTransitions refs
                ts <- if all (localts ==) remotets
                        then return []
@@ -307,13 +307,14 @@ get file = do
                        content <- if journalIgnorable st
                                then getRef fullname file
                                else if null (unmergedRefs st) 
-                                       then getLocal file
+                                       then lockJournal $ 
+                                               \jl -> getLocal jl file
                                        else unmergedbranchfallback st
                        setCache file content
                        return content
   where
        unmergedbranchfallback st = do
-               l <- getLocal file
+               l <- lockJournal $ \jl -> getLocal jl file
                bs <- forM (unmergedRefs st) $ \ref -> getRef ref file
                let content = l <> mconcat bs
                return $ applytransitions (unhandledTransitions st) content
@@ -343,7 +344,7 @@ precache file branchcontent = do
        st <- getState
        content <- if journalIgnorable st
                then pure branchcontent
-               else getJournalFileStale (GetPrivate True) file >>= return . \case
+               else lockJournal $ \jl -> getJournalFile jl (GetPrivate True) file >>= return . \case
                        NoJournalledContent -> branchcontent
                        JournalledContent journalcontent -> journalcontent
                        PossiblyStaleJournalledContent journalcontent ->
@@ -354,13 +355,13 @@ precache file branchcontent = do
  - reflect changes in remotes.
  - (Changing the value this returns, and then merging is always the
  - same as using get, and then changing its value.) -}
-getLocal :: RawFilePath -> Annex L.ByteString
-getLocal = getLocal' (GetPrivate True)
+getLocal :: JournalLocked -> RawFilePath -> Annex L.ByteString
+getLocal jl = getLocal' jl (GetPrivate True)
 
-getLocal' :: GetPrivate -> RawFilePath -> Annex L.ByteString
-getLocal' getprivate file = do
+getLocal' :: JournalLocked -> GetPrivate -> RawFilePath -> Annex L.ByteString
+getLocal' jl getprivate file = do
        fastDebug "Annex.Branch" ("read " ++ fromRawFilePath file)
-       go =<< getJournalFileStale getprivate file
+       go =<< getJournalFile jl getprivate file
   where
        go NoJournalledContent = getRef fullname file
        go (JournalledContent journalcontent) = return journalcontent
@@ -394,12 +395,12 @@ getRef ref file = withIndex $ catFile ref file
  - modifes the current content of the file on the branch.
  -}
 change :: Journalable content => RegardingUUID -> RawFilePath -> (L.ByteString -> content) -> Annex ()
-change ru file f = lockJournal $ \jl -> f <$> getToChange ru file >>= set jl ru file
+change ru file f = lockJournal $ \jl -> f <$> getToChange jl ru file >>= set jl ru file
 
 {- Applies a function which can modify the content of a file, or not. -}
 maybeChange :: Journalable content => RegardingUUID -> RawFilePath -> (L.ByteString -> Maybe content) -> Annex ()
 maybeChange ru file f = lockJournal $ \jl -> do
-       v <- getToChange ru file
+       v <- getToChange jl ru file
        case f v of
                Just jv ->
                        let b = journalableByteString jv
@@ -446,8 +447,8 @@ changeOrAppend ru file f = lockJournal $ \jl ->
                                        oldc <> journalableByteString toappend
 
 {- Only get private information when the RegardingUUID is itself private. -}
-getToChange :: RegardingUUID -> RawFilePath -> Annex L.ByteString
-getToChange ru f = flip getLocal' f . GetPrivate =<< regardingPrivateUUID ru
+getToChange :: JournalLocked -> RegardingUUID -> RawFilePath -> Annex L.ByteString
+getToChange jl ru f = flip (getLocal' jl) f . GetPrivate =<< regardingPrivateUUID ru
 
 {- Records new content of a file into the journal.
  -
@@ -727,10 +728,10 @@ stageJournal jl commitindex = withIndex $ withOtherTmp $ \tmpdir -> do
                removeWhenExistsWith (R.removeLink) (toRawFilePath jlogf)
        openjlog tmpdir = liftIO $ openTmpFileIn tmpdir "jlog"
 
-getLocalTransitions :: Annex Transitions
-getLocalTransitions = 
+getLocalTransitions :: JournalLocked -> Annex Transitions
+getLocalTransitions jl = 
        parseTransitionsStrictly "local"
-               <$> getLocal transitionsLog
+               <$> getLocal jl transitionsLog
 
 {- This is run after the refs have been merged into the index,
  - but before the result is committed to the branch.
@@ -979,7 +980,7 @@ overBranchFileContents' select go st = do
        -- Check the journal, in case it did not get committed to the branch
        checkjournal f branchcontent
                | journalIgnorable st = return branchcontent
-               | otherwise = getJournalFileStale (GetPrivate True) f >>= return . \case
+               | otherwise = lockJournal $ \jl -> getJournalFile jl (GetPrivate True) f >>= return . \case
                        NoJournalledContent -> branchcontent
                        JournalledContent journalledcontent ->
                                Just journalledcontent
@@ -989,7 +990,7 @@ overBranchFileContents' select go st = do
        drain buf fs = case getnext fs of
                Just (v, f, fs') -> do
                        liftIO $ putMVar buf fs'
-                       content <- getJournalFileStale (GetPrivate True) f >>= \case
+                       content <- lockJournal $ \jl -> getJournalFile jl (GetPrivate True) f >>= \case
                                NoJournalledContent -> return Nothing
                                JournalledContent journalledcontent ->
                                        return (Just journalledcontent)