automatically launch git repository repair

Added a RemoteChecker thread, that waits for problems to be reported with
remotes, and checks if their git repository is in need of repair.

Currently, only failures to sync with the remote cause a problem to be
reported. This seems enough, but we'll see.

Plugging in a removable drive with a repository on it that is corrupted
does automatically repair the repository, as long as the corruption causes
git push or git pull to fail. Some types of corruption do not, eg
missing/corrupt objects for blobs that git push doesn't need to look at.

So, this is not really a replacement for scheduled git repository fscking.
But it does make the assistant more robust.

This commit is sponsored by Fernando Jimenez.

Assistant/Threads/Cronner.hs

@@ -5,7 +5,7 @@
  - Licensed under the GNU GPL version 3 or higher.
  -}
 
-{-# LANGUAGE DeriveDataTypeable, CPP #-}
+{-# LANGUAGE DeriveDataTypeable #-}
 
 module Assistant.Threads.Cronner (
 	cronnerThread
@@ -29,10 +29,6 @@ import Assistant.Types.UrlRenderer
 import Assistant.Alert
 import Remote
 import qualified Types.Remote as Remote
-#ifdef WITH_WEBAPP
-import Assistant.WebApp.Types
-#endif
-import Git.Remote (RemoteName)
 import qualified Git.Fsck
 import Assistant.Repair
 import qualified Git
@@ -43,8 +39,6 @@ import Data.Time.LocalTime
 import Data.Time.Clock
 import qualified Data.Map as M
 import qualified Data.Set as S
-import qualified Control.Exception as E
-import qualified Data.Text as T
 
 {- Loads schedules for this repository, and fires off one thread for each 
  - scheduled event that runs on this repository. Each thread sleeps until
@@ -191,7 +185,7 @@ runActivity' urlrenderer (ScheduledSelfFsck _ d) = do
 		void $ batchCommand program (Param "fsck" : annexFsckParams d)
 		Git.Fsck.findBroken True g
 	u <- liftAnnex getUUID
-	repairWhenNecessary urlrenderer u Nothing fsckresults
+	void $ repairWhenNecessary urlrenderer u Nothing fsckresults
 	mapM_ reget =<< liftAnnex (dirKeys gitAnnexBadDir)
   where
 	reget k = queueTransfers "fsck found bad file; redownloading" Next k Nothing Download
@@ -220,18 +214,7 @@ runActivity' urlrenderer (ScheduledRemoteFsck u s d) = handle =<< liftAnnex (rem
 			if Git.repoIsLocal r && not (Git.repoIsLocalUnknown r)
 				then Just <$> Git.Fsck.findBroken True r
 				else pure Nothing
-		maybe noop (repairWhenNecessary urlrenderer u (Just rmt)) fsckresults
-
-showFscking :: UrlRenderer -> Maybe RemoteName -> IO (Either E.SomeException a) -> Assistant a
-showFscking urlrenderer remotename a = do
-#ifdef WITH_WEBAPP
-	button <- mkAlertButton False (T.pack "Configure") urlrenderer ConfigFsckR
-	r <- alertDuring (fsckAlert button remotename) $
-		liftIO a
-	either (liftIO . E.throwIO) return r
-#else
-	a
-#endif
+		maybe noop (void . repairWhenNecessary urlrenderer u (Just rmt)) fsckresults
 
 annexFsckParams :: Duration -> [CommandParam]
 annexFsckParams d =

Assistant/Threads/Pusher.hs

@@ -13,6 +13,7 @@ import Assistant.Pushes
 import Assistant.DaemonStatus
 import Assistant.Sync
 import Utility.ThreadScheduler
+import qualified Remote
 import qualified Types.Remote as Remote
 
 {- This thread retries pushes that failed before. -}
@@ -42,7 +43,7 @@ pushThread = namedThread "Pusher" $ runEvery (Seconds 2) <~> do
  - to avoid ugly messages when a removable drive is not attached.
  -}
 pushTargets :: Assistant [Remote]
-pushTargets = liftIO . filterM available =<< candidates <$> getDaemonStatus
+pushTargets = liftIO . filterM (Remote.checkAvailable True)
+	=<< candidates <$> getDaemonStatus
   where
 	candidates = filter (not . Remote.readonly) . syncGitRemotes
-	available = maybe (return True) doesDirectoryExist . Remote.localpath

Assistant/Threads/RemoteChecker.hs

@@ -0,0 +1,46 @@
+{- git-annex assistant remote checker thread
+ -
+ - Copyright 2013 Joey Hess <joey@kitenet.net>
+ -
+ - Licensed under the GNU GPL version 3 or higher.
+ -}
+
+module Assistant.Threads.RemoteChecker (
+	remoteCheckerThread
+) where
+
+import Assistant.Common
+import Utility.ThreadScheduler
+import Assistant.Types.UrlRenderer
+import Assistant.Alert
+import Remote
+import qualified Types.Remote as Remote
+import qualified Git.Fsck
+import Assistant.Repair
+import qualified Git
+import Assistant.RemoteProblem
+import Assistant.Sync
+
+import Data.Function
+
+{- Waits for problems with remotes, and tries to fsck the remote and repair
+ - the problem. -}
+remoteCheckerThread :: UrlRenderer -> NamedThread
+remoteCheckerThread urlrenderer = namedThread "RemoteChecker" $ forever $ do
+	mapM_ (handleProblem urlrenderer)
+		=<< liftIO . filterM (checkAvailable True)
+		=<< nubremotes <$> getRemoteProblems
+	liftIO $ threadDelaySeconds (Seconds 60)
+  where
+	nubremotes = nubBy ((==) `on` Remote.uuid)
+
+handleProblem :: UrlRenderer -> Remote -> Assistant ()
+handleProblem urlrenderer rmt
+	| Git.repoIsLocal r && not (Git.repoIsLocalUnknown r) = do
+		fsckresults <- showFscking urlrenderer (Just $ Remote.name rmt) $ tryNonAsync $
+			Git.Fsck.findBroken True r
+		whenM (repairWhenNecessary urlrenderer (Remote.uuid rmt) (Just rmt) fsckresults) $
+			syncRemote rmt
+	| otherwise = noop
+  where
+	r = Remote.repo rmt