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|
{- git-annex assistant git merge thread
-
- Copyright 2012 Joey Hess <joey@kitenet.net>
-
- Licensed under the GNU GPL version 3 or higher.
-}
module Assistant.Threads.Merger where
import Assistant.Common
import Assistant.ThreadedMonad
import Utility.DirWatcher
import Utility.Types.DirWatcher
import qualified Git
import qualified Git.Merge
import qualified Git.Branch
import qualified Command.Sync
thisThread :: ThreadName
thisThread = "Merger"
{- This thread watches for changes to .git/refs/heads/synced/,
- which indicate incoming pushes. It merges those pushes into the
- currently checked out branch. -}
mergeThread :: ThreadState -> NamedThread
mergeThread st = thread $ do
g <- runThreadState st $ fromRepo id
let dir = Git.localGitDir g </> "refs" </> "heads" </> "synced"
createDirectoryIfMissing True dir
let hook a = Just $ runHandler g a
let hooks = mkWatchHooks
{ addHook = hook onAdd
, errHook = hook onErr
}
void $ watchDir dir (const False) hooks id
debug thisThread ["watching", dir]
where
thread = NamedThread thisThread
type Handler = Git.Repo -> FilePath -> Maybe FileStatus -> IO ()
{- Runs an action handler.
-
- Exceptions are ignored, otherwise a whole thread could be crashed.
-}
runHandler :: Git.Repo -> Handler -> FilePath -> Maybe FileStatus -> IO ()
runHandler g handler file filestatus = void $ do
either print (const noop) =<< tryIO go
where
go = handler g file filestatus
{- Called when there's an error with inotify. -}
onErr :: Handler
onErr _ msg _ = error msg
{- Called when a new branch ref is written.
-
- This relies on git's atomic method of updating branch ref files,
- which is to first write the new file to .lock, and then rename it
- over the old file. So, ignore .lock files, and the rename ensures
- the watcher sees a new file being added on each update.
-
- 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.
-}
onAdd :: Handler
onAdd g file _
| ".lock" `isSuffixOf` file = noop
| otherwise = do
let changedbranch = Git.Ref $
"refs" </> "heads" </> takeFileName file
current <- Git.Branch.current g
when (Just changedbranch == current) $ do
liftIO $ debug thisThread
[ "merging changes into"
, show current
]
void $ mergeBranch changedbranch g
mergeBranch :: Git.Ref -> Git.Repo -> IO Bool
mergeBranch = Git.Merge.mergeNonInteractive . Command.Sync.syncBranch
|
