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{- management of the git-annex branch
-
- Copyright 2011-2012 Joey Hess <joey@kitenet.net>
-
- Licensed under the GNU GPL version 3 or higher.
-}
module Annex.Branch (
fullname,
name,
hasOrigin,
hasSibling,
siblingBranches,
create,
update,
forceUpdate,
updateTo,
get,
change,
commit,
stage,
files,
) where
import qualified Data.ByteString.Lazy.Char8 as L
import Common.Annex
import Annex.BranchState
import Annex.Journal
import qualified Git
import qualified Git.Command
import qualified Git.Ref
import qualified Git.Branch
import qualified Git.UnionMerge
import qualified Git.UpdateIndex
import Git.HashObject
import Git.Types
import Git.FilePath
import Annex.CatFile
import Annex.Perms
import qualified Annex
{- Name of the branch that is used to store git-annex's information. -}
name :: Git.Ref
name = Git.Ref "git-annex"
{- Fully qualified name of the branch. -}
fullname :: Git.Ref
fullname = Git.Ref $ "refs/heads/" ++ show name
{- Branch's name in origin. -}
originname :: Git.Ref
originname = Git.Ref $ "origin/" ++ show name
{- Does origin/git-annex exist? -}
hasOrigin :: Annex Bool
hasOrigin = inRepo $ Git.Ref.exists originname
{- Does the git-annex branch or a sibling foo/git-annex branch exist? -}
hasSibling :: Annex Bool
hasSibling = not . null <$> siblingBranches
{- List of git-annex (refs, branches), including the main one and any
- from remotes. Duplicate refs are filtered out. -}
siblingBranches :: Annex [(Git.Ref, Git.Branch)]
siblingBranches = inRepo $ Git.Ref.matchingUniq name
{- Creates the branch, if it does not already exist. -}
create :: Annex ()
create = void getBranch
{- Returns the ref of the branch, creating it first if necessary. -}
getBranch :: Annex Git.Ref
getBranch = maybe (hasOrigin >>= go >>= use) return =<< branchsha
where
go True = do
inRepo $ Git.Command.run "branch"
[Param $ show name, Param $ show originname]
fromMaybe (error $ "failed to create " ++ show name)
<$> branchsha
go False = withIndex' True $
inRepo $ Git.Branch.commit "branch created" fullname []
use sha = do
setIndexSha sha
return sha
branchsha = inRepo $ Git.Ref.sha fullname
{- Ensures that the branch and index are is up-to-date; should be
- called before data is read from it. Runs only once per git-annex run.
-}
update :: Annex ()
update = runUpdateOnce $ void $ updateTo =<< siblingBranches
{- Forces an update even if one has already been run. -}
forceUpdate :: Annex Bool
forceUpdate = updateTo =<< siblingBranches
{- Merges the specified Refs into the index, if they have any changes not
- already in it. The Branch names are only used in the commit message;
- it's even possible that the provided Branches have not been updated to
- point to the Refs yet.
-
- Before refs are merged into the index, it's important to first stage the
- journal into the index. Otherwise, any changes in the journal would
- later get staged, and might overwrite changes made during the merge.
- If no Refs are provided, the journal is still staged and committed.
-
- (It would be cleaner to handle the merge by updating the journal, not the
- index, with changes from the branches.)
-
- The branch is fast-forwarded if possible, otherwise a merge commit is
- made.
-
- Returns True if any refs were merged in, False otherwise.
-}
updateTo :: [(Git.Ref, Git.Branch)] -> Annex Bool
updateTo pairs = do
-- ensure branch exists, and get its current ref
branchref <- getBranch
-- check what needs updating before taking the lock
dirty <- unCommitted
(refs, branches) <- unzip <$> filterM isnewer pairs
if not dirty && null refs
then updateIndex branchref
else withIndex $ lockJournal $ do
when dirty stageJournal
let merge_desc = if null branches
then "update"
else "merging " ++
unwords (map Git.Ref.describe branches) ++
" into " ++ show name
unless (null branches) $ do
showSideAction merge_desc
mergeIndex refs
ff <- if dirty
then return False
else inRepo $ Git.Branch.fastForward fullname refs
if ff
then updateIndex branchref
else commitBranch branchref merge_desc
(nub $ fullname:refs)
invalidateCache
return $ not $ null refs
where
isnewer (r, _) = inRepo $ Git.Branch.changed fullname r
{- Gets the content of a file on the branch, or content from the journal, or
- staged in the index.
-
- Returns an empty string if the file doesn't exist yet. -}
get :: FilePath -> Annex String
get = get' False
{- Like get, but does not merge the branch, so the info returned may not
- reflect changes in remotes. (Changing the value this returns, and then
- merging is always the same as using get, and then changing its value.) -}
getStale :: FilePath -> Annex String
getStale = get' True
get' :: Bool -> FilePath -> Annex String
get' staleok file = fromcache =<< getCache file
where
fromcache (Just content) = return content
fromcache Nothing = fromjournal =<< getJournalFile file
fromjournal (Just content) = cache content
fromjournal Nothing
| staleok = withIndex frombranch
| otherwise = withIndexUpdate $ frombranch >>= cache
frombranch = L.unpack <$> catFile fullname file
cache content = do
setCache file content
return content
{- Applies a function to modifiy the content of a file.
-
- Note that this does not cause the branch to be merged, it only
- modifes the current content of the file on the branch.
-}
change :: FilePath -> (String -> String) -> Annex ()
change file a = lockJournal $ a <$> getStale file >>= set file
{- Records new content of a file into the journal and cache. -}
set :: FilePath -> String -> Annex ()
set file content = do
setJournalFile file content
setCache file content
{- Stages the journal, and commits staged changes to the branch. -}
commit :: String -> Annex ()
commit message = whenM unCommitted $ lockJournal $ do
stageJournal
ref <- getBranch
withIndex $ commitBranch ref message [fullname]
{- Stages the journal, not making a commit to the branch. -}
stage :: Annex ()
stage = whenM journalDirty $ lockJournal $ do
stageJournal
setUnCommitted
{- Commits the staged changes in the index to the branch.
-
- Ensures that the branch's index file is first updated to the state
- of the branch at branchref, before running the commit action. This
- is needed because the branch may have had changes pushed to it, that
- are not yet reflected in the index.
-
- Also safely handles a race that can occur if a change is being pushed
- into the branch at the same time. When the race happens, the commit will
- be made on top of the newly pushed change, but without the index file
- being updated to include it. The result is that the newly pushed
- change is reverted. This race is detected and another commit made
- to fix it.
-
- The branchref value can have been obtained using getBranch at any
- previous point, though getting it a long time ago makes the race
- more likely to occur.
-}
commitBranch :: Git.Ref -> String -> [Git.Ref] -> Annex ()
commitBranch branchref message parents = do
updateIndex branchref
committedref <- inRepo $ Git.Branch.commit message fullname parents
setIndexSha committedref
parentrefs <- commitparents <$> catObject committedref
when (racedetected branchref parentrefs) $
fixrace committedref parentrefs
setCommitted
where
-- look for "parent ref" lines and return the refs
commitparents = map (Git.Ref . snd) . filter isparent .
map (toassoc . L.unpack) . L.lines
toassoc = separate (== ' ')
isparent (k,_) = k == "parent"
{- The race can be detected by checking the commit's
- parent, which will be the newly pushed branch,
- instead of the expected ref that the index was updated to. -}
racedetected expectedref parentrefs
| expectedref `elem` parentrefs = False -- good parent
| otherwise = True -- race!
{- To recover from the race, union merge the lost refs
- into the index, and recommit on top of the bad commit. -}
fixrace committedref lostrefs = do
mergeIndex lostrefs
commitBranch committedref racemessage [committedref]
racemessage = message ++ " (recovery from race)"
{- Lists all files on the branch. There may be duplicates in the list. -}
files :: Annex [FilePath]
files = withIndexUpdate $ do
bfiles <- inRepo $ Git.Command.pipeNullSplit
[Params "ls-tree --name-only -r -z", Param $ show fullname]
jfiles <- getJournalledFiles
return $ jfiles ++ bfiles
{- Populates the branch's index file with the current branch contents.
-
- This is only done when the index doesn't yet exist, and the index
- is used to build up changes to be commited to the branch, and merge
- in changes from other branches.
-}
genIndex :: Git.Repo -> IO ()
genIndex g = Git.UpdateIndex.streamUpdateIndex g
[Git.UpdateIndex.lsTree fullname g]
{- Merges the specified refs into the index.
- Any changes staged in the index will be preserved. -}
mergeIndex :: [Git.Ref] -> Annex ()
mergeIndex branches = do
h <- catFileHandle
inRepo $ \g -> Git.UnionMerge.mergeIndex h g branches
{- Runs an action using the branch's index file. -}
withIndex :: Annex a -> Annex a
withIndex = withIndex' False
withIndex' :: Bool -> Annex a -> Annex a
withIndex' bootstrapping a = do
f <- fromRepo gitAnnexIndex
g <- gitRepo
let g' = g { gitEnv = Just [("GIT_INDEX_FILE", f)] }
Annex.changeState $ \s -> s { Annex.repo = g' }
checkIndexOnce $ unlessM (liftIO $ doesFileExist f) $ do
unless bootstrapping create
liftIO $ createDirectoryIfMissing True $ takeDirectory f
unless bootstrapping $ inRepo genIndex
r <- a
Annex.changeState $ \s -> s { Annex.repo = (Annex.repo s) { gitEnv = gitEnv g} }
return r
{- Runs an action using the branch's index file, first making sure that
- the branch and index are up-to-date. -}
withIndexUpdate :: Annex a -> Annex a
withIndexUpdate a = update >> withIndex a
{- Updates the branch's index to reflect the current contents of the branch.
- Any changes staged in the index will be preserved.
-
- Compares the ref stored in the lock file with the current
- ref of the branch to see if an update is needed.
-}
updateIndex :: Git.Ref -> Annex ()
updateIndex branchref = do
lock <- fromRepo gitAnnexIndexLock
lockref <- Git.Ref . firstLine <$>
liftIO (catchDefaultIO (readFileStrict lock) "")
when (lockref /= branchref) $ do
withIndex $ mergeIndex [fullname]
setIndexSha branchref
{- Record that the branch's index has been updated to correspond to a
- given ref of the branch. -}
setIndexSha :: Git.Ref -> Annex ()
setIndexSha ref = do
lock <- fromRepo gitAnnexIndexLock
liftIO $ writeFile lock $ show ref ++ "\n"
setAnnexPerm lock
{- Checks if there are uncommitted changes in the branch's index or journal. -}
unCommitted :: Annex Bool
unCommitted = do
d <- liftIO . doesFileExist =<< fromRepo gitAnnexIndexDirty
if d
then return d
else journalDirty
setUnCommitted :: Annex ()
setUnCommitted = do
file <- fromRepo gitAnnexIndexDirty
liftIO $ writeFile file "1"
setCommitted :: Annex ()
setCommitted = void $ do
file <- fromRepo gitAnnexIndexDirty
liftIO $ tryIO $ removeFile file
{- Stages the journal into the index. -}
stageJournal :: Annex ()
stageJournal = do
showStoringStateAction
fs <- getJournalFiles
withIndex $ do
g <- gitRepo
liftIO $ do
h <- hashObjectStart g
Git.UpdateIndex.streamUpdateIndex g
[genstream (gitAnnexJournalDir g) h fs]
hashObjectStop h
where
genstream dir h fs streamer = forM_ fs $ \file -> do
let path = dir </> file
sha <- hashFile h path
_ <- streamer $ Git.UpdateIndex.updateIndexLine
sha FileBlob (asTopFilePath $ fileJournal file)
removeFile path
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