no locking of journal on read after all

Finally have a final design, and it turns out not to need locking on read.

diff --git a/Annex/Branch.hs b/Annex/Branch.hs
index 00b71a830ee3ad0c6acbdc62c4118a25d7fdb117..456d9d6619309a0417cf4a35f5eef004744cdeda 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 jl
+               localtransitions <- getLocalTransitions
                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 <- lockJournal getLocalTransitions
+               localts <- getLocalTransitions
                remotets <- mapM getRefTransitions refs
                ts <- if all (localts ==) remotets
                        then return []
@@ -307,14 +307,13 @@ get file = do
                        content <- if journalIgnorable st
                                then getRef fullname file
                                else if null (unmergedRefs st) 
-                                       then lockJournal $ 
-                                               \jl -> getLocal jl file
+                                       then getLocal file
                                        else unmergedbranchfallback st
                        setCache file content
                        return content
   where
        unmergedbranchfallback st = do
-               l <- lockJournal $ \jl -> getLocal jl file
+               l <- getLocal file
                bs <- forM (unmergedRefs st) $ \ref -> getRef ref file
                let content = l <> mconcat bs
                return $ applytransitions (unhandledTransitions st) content
@@ -344,7 +343,7 @@ precache file branchcontent = do
        st <- getState
        content <- if journalIgnorable st
                then pure branchcontent
-               else lockJournal $ \jl -> getJournalFile jl (GetPrivate True) file >>= return . \case
+               else getJournalFileStale (GetPrivate True) file >>= return . \case
                        NoJournalledContent -> branchcontent
                        JournalledContent journalcontent -> journalcontent
                        PossiblyStaleJournalledContent journalcontent ->
@@ -355,13 +354,13 @@ 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 :: JournalLocked -> RawFilePath -> Annex L.ByteString
-getLocal jl = getLocal' jl (GetPrivate True)
+getLocal :: RawFilePath -> Annex L.ByteString
+getLocal = getLocal' (GetPrivate True)
 
-getLocal' :: JournalLocked -> GetPrivate -> RawFilePath -> Annex L.ByteString
-getLocal' jl getprivate file = do
+getLocal' :: GetPrivate -> RawFilePath -> Annex L.ByteString
+getLocal' getprivate file = do
        fastDebug "Annex.Branch" ("read " ++ fromRawFilePath file)
-       go =<< getJournalFile jl getprivate file
+       go =<< getJournalFileStale getprivate file
   where
        go NoJournalledContent = getRef fullname file
        go (JournalledContent journalcontent) = return journalcontent
@@ -395,12 +394,12 @@ 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 jl ru file >>= set jl ru file
+change ru file f = lockJournal $ \jl -> f <$> getToChange 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 jl ru file
+       v <- getToChange ru file
        case f v of
                Just jv ->
                        let b = journalableByteString jv
@@ -425,7 +424,7 @@ changeOrAppend ru file f = lockJournal $ \jl ->
        checkCanAppendJournalFile jl ru file >>= \case
                Just appendable -> ifM (annexAlwaysCompact <$> Annex.getGitConfig)
                        ( do
-                               oldc <- getToChange jl ru file
+                               oldc <- getToChange ru file
                                case f oldc of
                                        Change newc -> set jl ru file newc
                                        Append toappend -> append jl file appendable toappend
@@ -438,7 +437,7 @@ changeOrAppend ru file f = lockJournal $ \jl ->
                                Append toappend -> append jl file appendable toappend
                        )
                Nothing -> do
-                       oldc <- getToChange jl ru file
+                       oldc <- getToChange ru file
                        case f oldc of
                                Change newc -> set jl ru file newc
                                -- Journal file does not exist yet, so
@@ -447,8 +446,8 @@ changeOrAppend ru file f = lockJournal $ \jl ->
                                        oldc <> journalableByteString toappend
 
 {- Only get private information when the RegardingUUID is itself private. -}
-getToChange :: JournalLocked -> RegardingUUID -> RawFilePath -> Annex L.ByteString
-getToChange jl ru f = flip (getLocal' jl) f . GetPrivate =<< regardingPrivateUUID ru
+getToChange :: RegardingUUID -> RawFilePath -> Annex L.ByteString
+getToChange ru f = flip getLocal' f . GetPrivate =<< regardingPrivateUUID ru
 
 {- Records new content of a file into the journal.
  -
@@ -728,10 +727,10 @@ stageJournal jl commitindex = withIndex $ withOtherTmp $ \tmpdir -> do
                removeWhenExistsWith (R.removeLink) (toRawFilePath jlogf)
        openjlog tmpdir = liftIO $ openTmpFileIn tmpdir "jlog"
 
-getLocalTransitions :: JournalLocked -> Annex Transitions
-getLocalTransitions jl = 
+getLocalTransitions :: Annex Transitions
+getLocalTransitions = 
        parseTransitionsStrictly "local"
-               <$> getLocal jl transitionsLog
+               <$> getLocal transitionsLog
 
 {- This is run after the refs have been merged into the index,
  - but before the result is committed to the branch.
@@ -980,7 +979,7 @@ 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 = lockJournal $ \jl -> getJournalFile jl (GetPrivate True) f >>= return . \case
+               | otherwise = getJournalFileStale (GetPrivate True) f >>= return . \case
                        NoJournalledContent -> branchcontent
                        JournalledContent journalledcontent ->
                                Just journalledcontent
@@ -990,7 +989,7 @@ overBranchFileContents' select go st = do
        drain buf fs = case getnext fs of
                Just (v, f, fs') -> do
                        liftIO $ putMVar buf fs'
-                       content <- lockJournal $ \jl -> getJournalFile jl (GetPrivate True) f >>= \case
+                       content <- getJournalFileStale (GetPrivate True) f >>= \case
                                NoJournalledContent -> return Nothing
                                JournalledContent journalledcontent ->
                                        return (Just journalledcontent)