add remote fsck interface

Currently only implemented for local git remotes. May try to add support
to git-annex-shell for ssh remotes later. Could concevably also be
supported by some special remote, although that seems unlikely.

Cronner user this when available, and when not falls back to
fsck --fast --from remote

git annex fsck --from does not itself use this interface.
To do so, I would need to pass --fast and all other options that influence
fsck on to the git annex fsck that it runs inside the remote. And that
seems like a lot of work for a result that would be no better than
cd remote; git annex fsck
This may need to be revisited if git-annex-shell gets support, since it
may be the case that the user cannot ssh to the server to run git-annex
fsck there, but can run git-annex-shell there.

This commit was sponsored by Damien Diederen.

Assistant/Alert.hs

@@ -15,6 +15,7 @@ import Assistant.Alert.Utility
 import qualified Remote
 import Utility.Tense
 import Logs.Transfer
+import Git.Remote (RemoteName)
 
 import Data.String
 import qualified Data.Text as T
@@ -149,9 +150,11 @@ sanityCheckFixAlert msg = Alert
 	alerthead = "The daily sanity check found and fixed a problem:"
 	alertfoot = "If these problems persist, consider filing a bug report."
 
-fsckAlert :: AlertButton -> Alert
-fsckAlert button = baseActivityAlert
-	{ alertData = [ UnTensed "Consistency check in progress" ]
+fsckAlert :: AlertButton -> Maybe RemoteName -> Alert
+fsckAlert button n = baseActivityAlert
+	{ alertData = case n of
+		Nothing -> [ UnTensed $ T.pack $ "Consistency check in progress" ]
+		Just remotename -> [ UnTensed $ T.pack $ "Consistency check of " ++ remotename ++ " in progress"]
 	, alertButton = Just button
 	}
 

Assistant/Threads/Cronner.hs

@@ -21,15 +21,17 @@ import Utility.Scheduled
 import Types.ScheduledActivity
 import Utility.ThreadScheduler
 import Utility.HumanTime
-import qualified Build.SysConfig
+import Utility.Batch
 import Assistant.TransferQueue
 import Annex.Content
 import Logs.Transfer
 import Assistant.Types.UrlRenderer
 import Assistant.Alert
+import Remote
 #ifdef WITH_WEBAPP
 import Assistant.WebApp.Types
 #endif
+import Git.Remote (RemoteName)
 
 import Control.Concurrent.Async
 import Data.Time.LocalTime
@@ -134,45 +136,44 @@ secondsUntilLocalTime t = do
 runActivity :: UrlRenderer -> ScheduledActivity -> Assistant ()
 runActivity urlrenderer (ScheduledSelfFsck _ d) = do
 	program <- liftIO $ readProgramFile
+	void $ runFsck urlrenderer Nothing $
+  		batchCommand program (Param "fsck" : fsckParams d)
+	mapM_ reget =<< liftAnnex (dirKeys gitAnnexBadDir)
+  where
+	reget k = queueTransfers "fsck found bad file; redownloading" Next k Nothing Download
+runActivity urlrenderer (ScheduledRemoteFsck u s d) = go =<< liftAnnex (remoteFromUUID u)
+  where
+	go (Just r) = void $ case Remote.remoteFsck r of
+		Nothing -> void $ runFsck urlrenderer (Just $ Remote.name r) $ do
+			program <- readProgramFile
+			batchCommand program $ 
+				[ Param "fsck"
+				-- avoid downloading files
+				, Param "--fast"
+				, Param "--from"
+				, Param $ Remote.name r
+				] ++ fsckParams d
+		Just mkfscker ->
+			{- Note that having mkfsker return an IO action
+			 - avoids running a long duration fsck in the
+			 - Annex monad. -}
+			void . runFsck urlrenderer (Just $ Remote.name r)
+				=<< liftAnnex (mkfscker (fsckParams d))
+	go Nothing = debug ["skipping remote fsck of uuid without a configured remote", fromUUID u, fromSchedule s]
+
+runFsck :: UrlRenderer -> Maybe RemoteName -> IO Bool -> Assistant Bool
+runFsck urlrenderer remotename a = do
 #ifdef WITH_WEBAPP
 	button <- mkAlertButton False (T.pack "Configure") urlrenderer ConfigFsckR
-	r <- alertDuring (fsckAlert button) $ liftIO $ do
-		E.try (runfsck program) :: IO (Either E.SomeException ExitCode)
-	either (liftIO . E.throwIO) (const noop) r
+	r <- alertDuring (fsckAlert button remotename) $ liftIO $ do
+		E.try a :: IO (Either E.SomeException Bool)
+	either (liftIO . E.throwIO) return r
 #else
-	runfsck program
+	a
 #endif
-	queueBad
-  where
-  	runfsck program = niceShell $
-		program ++ " fsck --incremental-schedule=1d --time-limit=" ++ fromDuration d
 
-runActivity _ (ScheduledRemoteFsck _ _ _) =
-	debug ["remote fsck not implemented yet"]
-
-queueBad :: Assistant ()
-queueBad = mapM_ queue =<< liftAnnex (dirKeys gitAnnexBadDir)
-  where
-	queue k = queueTransfers "fsck found bad file; redownloading" Next k Nothing Download
-
-{- Runs a shell command niced, until it terminates.
- - 
- - When an async exception is received, the command is sent a SIGTERM,
- - and after it finishes shutting down the exception is re-raised.  -}
-niceShell :: String -> IO ExitCode
-niceShell command = do
-	(_, _, _, pid) <- createProcess $ proc "sh"
-		[ "-c"
-		, "exec " ++ nicedcommand
+fsckParams :: Duration -> [CommandParam]
+fsckParams d =
+	[ Param "--incremental-schedule=1d"
+	, Param $ "--time-limit=" ++ fromDuration d
 	]
-	r <- E.try (waitForProcess pid) :: IO (Either E.SomeException ExitCode)
-	case r of
-		Right exitcode -> return exitcode
-		Left asyncexception -> do
-			terminateProcess pid
-			void $ waitForProcess pid
-			E.throwIO asyncexception
-  where
-  	nicedcommand
-		| Build.SysConfig.nice = "nice " ++ command
-		| otherwise = command

Remote.hs

@@ -16,6 +16,7 @@ module Remote (
 	hasKey,
 	hasKeyCheap,
 	whereisKey,
+	remoteFsck,
 
 	remoteTypes,
 	remoteList,

Remote/Bup.hs

@@ -63,6 +63,7 @@ gen r u c gc = do
 		, hasKey = checkPresent r bupr'
 		, hasKeyCheap = bupLocal buprepo
 		, whereisKey = Nothing
+		, remoteFsck = Nothing
 		, config = c
 		, repo = r
 		, gitconfig = gc

Remote/Directory.hs

@@ -54,6 +54,7 @@ gen r u c gc = do
 			hasKey = checkPresent dir chunksize,
 			hasKeyCheap = True,
 			whereisKey = Nothing,
+			remoteFsck = Nothing,
 			config = M.empty,
 			repo = r,
 			gitconfig = gc,

Remote/GCrypt.hs

@@ -107,6 +107,7 @@ gen' r u c gc = do
 		, hasKey = checkPresent this rsyncopts
 		, hasKeyCheap = repoCheap r
 		, whereisKey = Nothing
+		, remoteFsck = Nothing
 		, config = M.empty
 		, localpath = localpathCalc r
 		, repo = r

Remote/Git.hs

@@ -42,10 +42,12 @@ import Utility.Metered
 #ifndef mingw32_HOST_OS
 import Utility.CopyFile
 #endif
+import Utility.Batch
 import Remote.Helper.Git
 import Remote.Helper.Messages
 import qualified Remote.Helper.Ssh as Ssh
 import qualified Remote.GCrypt
+import Config.Files
 
 import Control.Concurrent
 import Control.Concurrent.MSampleVar
@@ -111,6 +113,9 @@ gen r u c gc
 			, hasKey = inAnnex r
 			, hasKeyCheap = repoCheap r
 			, whereisKey = Nothing
+			, remoteFsck = if Git.repoIsUrl r
+				then Nothing
+				else Just $ fsckOnRemote r
 			, config = M.empty
 			, localpath = localpathCalc r
 			, repo = r
@@ -396,6 +401,17 @@ copyToRemote r key file p
 							(\d -> rsyncOrCopyFile params object d p)
 			)
 
+fsckOnRemote :: Git.Repo -> [CommandParam] -> Annex (IO Bool)
+fsckOnRemote r params
+	| Git.repoIsUrl r = return $ do
+		program <- readProgramFile
+		batchCommand program $ Param "fsck" : params
+	| otherwise = do
+		s <- Ssh.git_annex_shell r "fsck" params []
+		return $ case s of
+			Nothing -> return False
+			Just (c, ps) -> batchCommand c ps
+
 {- Runs an action on a local repository inexpensively, by making an annex
  - monad using that repository. -}
 onLocal :: Git.Repo -> Annex a -> IO a

Remote/Glacier.hs

@@ -59,6 +59,7 @@ gen r u c gc = new <$> remoteCost gc veryExpensiveRemoteCost
 			hasKey = checkPresent this,
 			hasKeyCheap = False,
 			whereisKey = Nothing,
+			remoteFsck = Nothing,
 			config = c,
 			repo = r,
 			gitconfig = gc,

Remote/Hook.hs

@@ -52,6 +52,7 @@ gen r u c gc = do
 			hasKey = checkPresent r hooktype,
 			hasKeyCheap = False,
 			whereisKey = Nothing,
+			remoteFsck = Nothing,
 			config = M.empty,
 			localpath = Nothing,
 			repo = r,

Remote/Rsync.hs

@@ -79,6 +79,7 @@ gen r u c gc = do
 			, hasKey = checkPresent r o
 			, hasKeyCheap = False
 			, whereisKey = Nothing
+			, remoteFsck = Nothing
 			, config = M.empty
 			, repo = r
 			, gitconfig = gc

Remote/S3.hs

@@ -62,6 +62,7 @@ gen r u c gc = new <$> remoteCost gc expensiveRemoteCost
 			hasKey = checkPresent this,
 			hasKeyCheap = False,
 			whereisKey = Nothing,
+			remoteFsck = Nothing,
 			config = c,
 			repo = r,
 			gitconfig = gc,

Remote/Web.hs

@@ -56,6 +56,7 @@ gen r _ _ gc =
 		hasKey = checkKey,
 		hasKeyCheap = False,
 		whereisKey = Just getUrls,
+		remoteFsck = Nothing,
 		config = M.empty,
 		gitconfig = gc,
 		localpath = Nothing,

Remote/WebDAV.hs

@@ -65,6 +65,7 @@ gen r u c gc = new <$> remoteCost gc expensiveRemoteCost
 			hasKey = checkPresent this,
 			hasKeyCheap = False,
 			whereisKey = Nothing,
+			remoteFsck = Nothing,
 			config = c,
 			repo = r,
 			gitconfig = gc,

Types/Remote.hs

@@ -19,6 +19,7 @@ import Types.GitConfig
 import Config.Cost
 import Utility.Metered
 import Git.Remote
+import Utility.SafeCommand
 
 type RemoteConfigKey = String
 type RemoteConfig = M.Map RemoteConfigKey String
@@ -64,6 +65,10 @@ data RemoteA a = Remote {
 	hasKeyCheap :: Bool,
 	-- Some remotes can provide additional details for whereis.
 	whereisKey :: Maybe (Key -> a [String]),
+	-- Some remotes can run a fsck operation on the remote,
+	-- without transferring all the data to the local repo
+	-- The parameters are passed to the fsck command on the remote.
+	remoteFsck :: Maybe ([CommandParam] -> a (IO Bool)),
 	-- a Remote has a persistent configuration store
 	config :: RemoteConfig,
 	-- git repo for the Remote

Utility/Batch.hs

@@ -9,10 +9,14 @@
 
 module Utility.Batch where
 
+import Common
+import qualified Build.SysConfig
+
 #if defined(linux_HOST_OS) || defined(__ANDROID__)
 import Control.Concurrent.Async
 import System.Posix.Process
 #endif
+import qualified Control.Exception as E
 
 {- Runs an operation, at batch priority.
  -
@@ -38,3 +42,27 @@ batch a = a
 
 maxNice :: Int
 maxNice = 19
+
+{- Runs a command in a way that's suitable for batch jobs.
+ - The command is run niced. If the calling thread receives an async
+ - exception, it sends the command a SIGTERM, and after the command
+ - finishes shuttting down, it re-raises the async exception. -}
+batchCommand :: String -> [CommandParam] -> IO Bool
+batchCommand command params = do
+	(_, _, _, pid) <- createProcess $ proc "sh"
+		[ "-c"
+		, "exec " ++ nicedcommand
+		]
+	r <- E.try (waitForProcess pid) :: IO (Either E.SomeException ExitCode)
+	case r of
+		Right ExitSuccess -> return True
+		Right _ -> return False
+		Left asyncexception -> do
+			terminateProcess pid
+			void $ waitForProcess pid
+			E.throwIO asyncexception
+  where
+  	commandline = unwords $ map shellEscape $ command : toCommand params
+  	nicedcommand
+		| Build.SysConfig.nice = "nice " ++ commandline
+		| otherwise = commandline