301 lines
9.8 KiB
Haskell
301 lines
9.8 KiB
Haskell
{- management of the git-annex branch
|
|
-
|
|
- Copyright 2011 Joey Hess <joey@kitenet.net>
|
|
-
|
|
- Licensed under the GNU GPL version 3 or higher.
|
|
-}
|
|
|
|
module Annex.Branch (
|
|
name,
|
|
hasOrigin,
|
|
hasSibling,
|
|
create,
|
|
update,
|
|
get,
|
|
change,
|
|
commit,
|
|
files,
|
|
) where
|
|
|
|
import qualified Data.ByteString.Lazy.Char8 as L
|
|
|
|
import Common.Annex
|
|
import Annex.Exception
|
|
import Annex.BranchState
|
|
import Annex.Journal
|
|
import qualified Git
|
|
import qualified Git.Ref
|
|
import qualified Git.Branch
|
|
import qualified Git.UnionMerge
|
|
import qualified Git.HashObject
|
|
import Annex.CatFile
|
|
|
|
{- 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.matching name
|
|
|
|
{- Creates the branch, if it does not already exist. -}
|
|
create :: Annex ()
|
|
create = do
|
|
_ <- getBranch
|
|
return ()
|
|
|
|
{- 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.run "branch"
|
|
[Param $ show name, Param $ show originname]
|
|
fromMaybe (error $ "failed to create " ++ show name)
|
|
<$> branchsha
|
|
go False = withIndex' True $ do
|
|
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.
|
|
-
|
|
- 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.
|
|
-
|
|
- (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.
|
|
-}
|
|
update :: Annex ()
|
|
update = runUpdateOnce $ do
|
|
-- ensure branch exists, and get its current ref
|
|
branchref <- getBranch
|
|
-- check what needs updating before taking the lock
|
|
dirty <- journalDirty
|
|
(refs, branches) <- unzip <$> newerSiblings
|
|
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 branches
|
|
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
|
|
where
|
|
newerSiblings = filterM isnewer =<< siblingBranches
|
|
isnewer (_, b) = inRepo $ Git.Branch.changed fullname b
|
|
|
|
{- 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 $ getStale file >>= return . a >>= 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 journalDirty $ lockJournal $ do
|
|
stageJournal
|
|
ref <- getBranch
|
|
withIndex $ commitBranch ref message [fullname]
|
|
|
|
{- 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 brannch 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
|
|
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.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.UnionMerge.stream_update_index g
|
|
[Git.UnionMerge.ls_tree fullname g]
|
|
|
|
{- Merges the specified branches 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.merge_index 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
|
|
bracketIO (Git.useIndex f) id $ do
|
|
unlessM (liftIO $ doesFileExist f) $ do
|
|
unless bootstrapping create
|
|
liftIO $ createDirectoryIfMissing True $ takeDirectory f
|
|
unless bootstrapping $ inRepo genIndex
|
|
a
|
|
|
|
{- 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"
|
|
|
|
{- Stages the journal into the index. -}
|
|
stageJournal :: Annex ()
|
|
stageJournal = do
|
|
fs <- getJournalFiles
|
|
g <- gitRepo
|
|
withIndex $ liftIO $ do
|
|
let dir = gitAnnexJournalDir g
|
|
let paths = map (dir </>) fs
|
|
(shas, cleanup) <- Git.HashObject.hashFiles paths g
|
|
Git.UnionMerge.update_index g $
|
|
index_lines shas (map fileJournal fs)
|
|
cleanup
|
|
mapM_ removeFile paths
|
|
where
|
|
index_lines shas = map genline . zip shas
|
|
genline (sha, file) = Git.UnionMerge.update_index_line sha file
|