git-annex/Assistant/Threads/Merger.hs
Joey Hess 46e3319995
assistant: Deal with upcoming git's refusal to merge unrelated histories by default
git 2.8.1 (or perhaps 2.9.0) is going to prevent git merge from merging in
unrelated branches. Since the webapp's pairing etc features often combine
together repositories with unrelated histories, work around this behavior
change by setting GIT_MERGE_ALLOW_UNRELATED_HISTORIES when the assistant
merges.

Note though that this is not done for git annex sync's merges, so
it will follow git's default or configured behavior.
2016-04-22 14:26:44 -04:00

123 lines
3.4 KiB
Haskell

{- git-annex assistant git merge thread
-
- Copyright 2012 Joey Hess <id@joeyh.name>
-
- Licensed under the GNU GPL version 3 or higher.
-}
module Assistant.Threads.Merger where
import Assistant.Common
import Assistant.TransferQueue
import Assistant.BranchChange
import Assistant.DaemonStatus
import Assistant.ScanRemotes
import Assistant.Sync
import Utility.DirWatcher
import Utility.DirWatcher.Types
import qualified Annex.Branch
import qualified Git
import qualified Git.Branch
import qualified Command.Sync
import Annex.TaggedPush
import Remote (remoteFromUUID)
import qualified Data.Set as S
import qualified Data.Text as T
{- This thread watches for changes to .git/refs/, and handles incoming
- pushes. -}
mergeThread :: NamedThread
mergeThread = namedThread "Merger" $ do
g <- liftAnnex gitRepo
let dir = Git.localGitDir g </> "refs"
liftIO $ createDirectoryIfMissing True dir
let hook a = Just <$> asIO2 (runHandler a)
changehook <- hook onChange
errhook <- hook onErr
let hooks = mkWatchHooks
{ addHook = changehook
, modifyHook = changehook
, errHook = errhook
}
void $ liftIO $ watchDir dir (const False) True hooks id
debug ["watching", dir]
type Handler = FilePath -> Assistant ()
{- Runs an action handler.
-
- Exceptions are ignored, otherwise a whole thread could be crashed.
-}
runHandler :: Handler -> FilePath -> Maybe FileStatus -> Assistant ()
runHandler handler file _filestatus =
either (liftIO . print) (const noop) =<< tryIO <~> handler file
{- Called when there's an error with inotify. -}
onErr :: Handler
onErr = error
{- Called when a new branch ref is written, or a branch ref is modified.
-
- At startup, synthetic add events fire, causing this to run, but that's
- ok; it ensures that any changes pushed since the last time the assistant
- ran are merged in.
-}
onChange :: Handler
onChange file
| ".lock" `isSuffixOf` file = noop
| isAnnexBranch file = do
branchChanged
diverged <- liftAnnex Annex.Branch.forceUpdate
when diverged $
unlessM handleDesynced $
queueDeferredDownloads "retrying deferred download" Later
| "/synced/" `isInfixOf` file =
mergecurrent =<< liftAnnex (join Command.Sync.getCurrBranch)
| otherwise = noop
where
changedbranch = fileToBranch file
mergecurrent currbranch@(Just b, _)
| equivBranches changedbranch b =
whenM (liftAnnex $ inRepo $ Git.Branch.changed b changedbranch) $ do
debug
[ "merging", Git.fromRef changedbranch
, "into", Git.fromRef b
]
void $ liftAnnex $ Command.Sync.merge
currbranch mergeConfig
Git.Branch.AutomaticCommit
changedbranch
mergecurrent _ = noop
handleDesynced = case fromTaggedBranch changedbranch of
Nothing -> return False
Just (u, info) -> do
mr <- liftAnnex $ remoteFromUUID u
case mr of
Nothing -> return False
Just r -> do
s <- desynced <$> getDaemonStatus
if S.member u s || Just (T.unpack $ getXMPPClientID r) == info
then do
modifyDaemonStatus_ $ \st -> st
{ desynced = S.delete u s }
addScanRemotes True [r]
return True
else return False
equivBranches :: Git.Ref -> Git.Ref -> Bool
equivBranches x y = base x == base y
where
base = takeFileName . Git.fromRef
isAnnexBranch :: FilePath -> Bool
isAnnexBranch f = n `isSuffixOf` f
where
n = '/' : Git.fromRef Annex.Branch.name
fileToBranch :: FilePath -> Git.Ref
fileToBranch f = Git.Ref $ "refs" </> base
where
base = Prelude.last $ split "/refs/" f