fsck --from remote --fast

Avoids expensive file transfers, at the expense of checking file size
and/or contents.

Required some reworking of the remote code.

Annex/Content.hs

@@ -306,9 +306,18 @@ downloadUrl urls file = do
 
 {- Copies a key's content, when present, to a temp file.
  - This is used to speed up some rsyncs. -}
-preseedTmp :: Key -> FilePath -> Annex ()
-preseedTmp key file =
-	unlessM (liftIO $ doesFileExist file) $ whenM (inAnnex key) $ do
+preseedTmp :: Key -> FilePath -> Annex Bool
+preseedTmp key file = go =<< inAnnex key
+	where
+		go False = return False
+		go True = do
+			ok <- copy
+			when ok $ liftIO $ allowWrite file
+			return ok
+		copy = do
+			present <- liftIO $ doesFileExist file
+			if present
+				then return True
+				else do
 					s <- inRepo $ gitAnnexLocation key
-		liftIO $ whenM (copyFileExternal s file) $
-			allowWrite file
+					liftIO $ copyFileExternal s file

Command/Fsck.hs

@@ -9,6 +9,7 @@ module Command.Fsck where
 
 import Common.Annex
 import Command
+import qualified Annex
 import qualified Remote
 import qualified Types.Backend
 import qualified Types.Key
@@ -65,8 +66,8 @@ performRemote key file backend numcopies remote = do
 			showNote err
 			stop
 		Right True -> withtmp $ \tmpfile -> do
-			copied <- Remote.retrieveKeyFile remote key True tmpfile
-			if copied then go True (Just tmpfile) else go False Nothing
+			copied <- getfile tmpfile
+			if copied then go True (Just tmpfile) else go True Nothing
 		Right False -> go False Nothing
 	where
 		go present localcopy = check
@@ -83,6 +84,15 @@ performRemote key file backend numcopies remote = do
 			let cleanup = liftIO $ catch (removeFile tmp) (const $ return ())
 			cleanup
 			cleanup `after` a tmp
+		getfile tmp = do
+			ok <- Remote.retrieveKeyFileCheap remote key tmp
+			if ok
+				then return ok
+				else do
+					fast <- Annex.getState Annex.fast
+					if fast
+						then return False
+						else Remote.retrieveKeyFile remote key tmp
 
 {- To fsck a bare repository, fsck each key in the location log. -}
 withBarePresentKeys :: (Key -> CommandStart) -> CommandSeek

Command/Get.hs

@@ -72,7 +72,7 @@ getKeyFile key file = do
 				else return True
 		docopy r continue = do
 			showAction $ "from " ++ Remote.name r
-			copied <- Remote.retrieveKeyFile r key False file
+			copied <- Remote.retrieveKeyFile r key file
 			if copied
 				then return True
 				else continue

Command/Move.hs

@@ -131,7 +131,7 @@ fromPerform src move key = moveLock move key $ do
 		then handle move True
 		else do
 			showAction $ "from " ++ Remote.name src
-			ok <- getViaTmp key $ Remote.retrieveKeyFile src key False
+			ok <- getViaTmp key $ Remote.retrieveKeyFile src key
 			handle move ok
 	where
 		handle _ False = stop -- failed

Remote.hs

@@ -11,6 +11,7 @@ module Remote (
 	name,
 	storeKey,
 	retrieveKeyFile,
+	retrieveKeyFileCheap,
 	removeKey,
 	hasKey,
 	hasKeyCheap,

Remote/Bup.hs

@@ -50,6 +50,7 @@ gen r u c = do
 			name = Git.repoDescribe r,
  			storeKey = store r buprepo,
 			retrieveKeyFile = retrieve buprepo,
+			retrieveKeyFileCheap = retrieveCheap buprepo,
 			removeKey = remove,
 			hasKey = checkPresent r bupr',
 			hasKeyCheap = bupLocal buprepo,
@@ -118,13 +119,16 @@ storeEncrypted r buprepo (cipher, enck) k = do
 		withEncryptedHandle cipher (L.readFile src) $ \h ->
 			pipeBup params (Just h) Nothing
 
-retrieve :: BupRepo -> Key -> Bool -> FilePath -> Annex Bool
-retrieve buprepo k _ f = do
+retrieve :: BupRepo -> Key -> FilePath -> Annex Bool
+retrieve buprepo k f = do
 	let params = bupParams "join" buprepo [Param $ show k]
 	liftIO $ catchBoolIO $ do
 		tofile <- openFile f WriteMode
 		pipeBup params Nothing (Just tofile)
 
+retrieveCheap :: BupRepo -> Key -> FilePath -> Annex Bool
+retrieveCheap _ _ _ = return False
+
 retrieveEncrypted :: BupRepo -> (Cipher, Key) -> FilePath -> Annex Bool
 retrieveEncrypted buprepo (cipher, enck) f = do
 	let params = bupParams "join" buprepo [Param $ show enck]

Remote/Directory.hs

@@ -41,6 +41,7 @@ gen r u c = do
 			name = Git.repoDescribe r,
  			storeKey = store dir,
 			retrieveKeyFile = retrieve dir,
+			retrieveKeyFileCheap = retrieveCheap dir,
 			removeKey = remove dir,
 			hasKey = checkPresent dir,
 			hasKeyCheap = True,
@@ -109,11 +110,12 @@ storeHelper d key a = do
 		preventWrite dir
 	return ok
 
-retrieve :: FilePath -> Key -> Bool -> FilePath -> Annex Bool
-retrieve d k tmp f = liftIO $ withStoredFile d k $ \file ->
-	if tmp
-		then catchBoolIO $ createSymbolicLink file f >> return True
-		else copyFileExternal file f
+retrieve :: FilePath -> Key -> FilePath -> Annex Bool
+retrieve d k f = liftIO $ withStoredFile d k $ \file -> copyFileExternal file f
+
+retrieveCheap :: FilePath -> Key -> FilePath -> Annex Bool
+retrieveCheap d k f = liftIO $ withStoredFile d k $ \file ->
+	catchBoolIO $ createSymbolicLink file f >> return True
 
 retrieveEncrypted :: FilePath -> (Cipher, Key) -> FilePath -> Annex Bool
 retrieveEncrypted d (cipher, enck) f =

Remote/Git.hs

@@ -75,6 +75,7 @@ gen r u _ = do
 		name = Git.repoDescribe r',
 		storeKey = copyToRemote r',
 		retrieveKeyFile = copyFromRemote r',
+		retrieveKeyFileCheap = copyFromRemoteCheap r',
 		removeKey = dropKey r',
 		hasKey = inAnnex r',
 		hasKeyCheap = cheap,
@@ -198,20 +199,28 @@ dropKey r key
 		]
 
 {- Tries to copy a key's content from a remote's annex to a file. -}
-copyFromRemote :: Git.Repo -> Key -> Bool -> FilePath -> Annex Bool
-copyFromRemote r key tmp file
+copyFromRemote :: Git.Repo -> Key -> FilePath -> Annex Bool
+copyFromRemote r key file
 	| not $ Git.repoIsUrl r = do
 		params <- rsyncParams r
 		loc <- liftIO $ gitAnnexLocation key r
-		if tmp
-			then liftIO $ catchBoolIO $ createSymbolicLink loc file >> return True
-			else rsyncOrCopyFile params loc file
-	| Git.repoIsSsh r = do
-		when tmp $ Annex.Content.preseedTmp key file
-		rsyncHelper =<< rsyncParamsRemote r True key file
+		rsyncOrCopyFile params loc file
+	| Git.repoIsSsh r = rsyncHelper =<< rsyncParamsRemote r True key file
 	| Git.repoIsHttp r = Annex.Content.downloadUrl (keyUrls r key) file
 	| otherwise = error "copying from non-ssh, non-http repo not supported"
 
+copyFromRemoteCheap :: Git.Repo -> Key -> FilePath -> Annex Bool
+copyFromRemoteCheap r key file
+	| not $ Git.repoIsUrl r = do
+		loc <- liftIO $ gitAnnexLocation key r
+		liftIO $ catchBoolIO $ createSymbolicLink loc file >> return True
+	| Git.repoIsSsh r = do
+		ok <- Annex.Content.preseedTmp key file
+		if ok
+			then copyFromRemote r key file
+			else return False
+	| otherwise = return False
+
 {- Tries to copy a key's content to a remote's annex. -}
 copyToRemote :: Git.Repo -> Key -> Annex Bool
 copyToRemote r key

Remote/Helper/Encryptable.hs

@@ -47,6 +47,7 @@ encryptableRemote c storeKeyEncrypted retrieveKeyFileEncrypted r =
 	r {
 		storeKey = store,
 		retrieveKeyFile = retrieve,
+		retrieveKeyFileCheap = retrieveCheap,
 		removeKey = withkey $ removeKey r,
 		hasKey = withkey $ hasKey r,
 		cost = cost r + encryptedRemoteCostAdj
@@ -55,9 +56,12 @@ encryptableRemote c storeKeyEncrypted retrieveKeyFileEncrypted r =
 		store k = cip k >>= maybe
 			(storeKey r k)
 			(`storeKeyEncrypted` k)
-		retrieve k t f = cip k >>= maybe
-			(retrieveKeyFile r k t f)
+		retrieve k f = cip k >>= maybe
+			(retrieveKeyFile r k f)
 			(`retrieveKeyFileEncrypted` f)
+		retrieveCheap k f = cip k >>= maybe
+			(retrieveKeyFileCheap r k f)
+			(\_ -> return False)
 		withkey a k = cip k >>= maybe (a k) (a . snd)
 		cip = cipherKey c
 

Remote/Hook.hs

@@ -41,6 +41,7 @@ gen r u c = do
 			name = Git.repoDescribe r,
  			storeKey = store hooktype,
 			retrieveKeyFile = retrieve hooktype,
+			retrieveKeyFileCheap = retrieveCheap hooktype,
 			removeKey = remove hooktype,
 			hasKey = checkPresent r hooktype,
 			hasKeyCheap = False,
@@ -106,8 +107,11 @@ storeEncrypted h (cipher, enck) k = withTmp enck $ \tmp -> do
 	liftIO $ withEncryptedContent cipher (L.readFile src) $ L.writeFile tmp
 	runHook h "store" enck (Just tmp) $ return True
 
-retrieve :: String -> Key -> Bool -> FilePath -> Annex Bool
-retrieve h k _ f = runHook h "retrieve" k (Just f) $ return True
+retrieve :: String -> Key -> FilePath -> Annex Bool
+retrieve h k f = runHook h "retrieve" k (Just f) $ return True
+
+retrieveCheap :: String -> Key -> FilePath -> Annex Bool
+retrieveCheap _ _ _ = return False
 
 retrieveEncrypted :: String -> (Cipher, Key) -> FilePath -> Annex Bool
 retrieveEncrypted h (cipher, enck) f = withTmp enck $ \tmp ->

Remote/Rsync.hs

@@ -48,6 +48,7 @@ gen r u c = do
 			name = Git.repoDescribe r,
  			storeKey = store o,
 			retrieveKeyFile = retrieve o,
+			retrieveKeyFileCheap = retrieveCheap o,
 			removeKey = remove o,
 			hasKey = checkPresent r o,
 			hasKeyCheap = False,
@@ -102,19 +103,24 @@ storeEncrypted o (cipher, enck) k = withTmp enck $ \tmp -> do
 	liftIO $ withEncryptedContent cipher (L.readFile src) $ L.writeFile tmp
 	rsyncSend o enck tmp
 
-retrieve :: RsyncOpts -> Key -> Bool -> FilePath -> Annex Bool
-retrieve o k tmp f = untilTrue (rsyncUrls o k) $ \u -> do
-	when tmp $ preseedTmp k f
-	rsyncRemote o
+retrieve :: RsyncOpts -> Key -> FilePath -> Annex Bool
+retrieve o k f = untilTrue (rsyncUrls o k) $ \u -> rsyncRemote o
 	-- use inplace when retrieving to support resuming
 	[ Param "--inplace"
 	, Param u
 	, Param f
 	]
 
+retrieveCheap :: RsyncOpts -> Key -> FilePath -> Annex Bool
+retrieveCheap o k f = do
+	ok <- preseedTmp k f
+	if ok
+		then retrieve o k f
+		else return False
+
 retrieveEncrypted :: RsyncOpts -> (Cipher, Key) -> FilePath -> Annex Bool
 retrieveEncrypted o (cipher, enck) f = withTmp enck $ \tmp -> do
-	res <- retrieve o enck False tmp
+	res <- retrieve o enck tmp
 	if res
 		then liftIO $ catchBoolIO $ do
 			withDecryptedContent cipher (L.readFile tmp) $ L.writeFile f

Remote/S3.hs

@@ -53,6 +53,7 @@ gen' r u c cst =
 			name = Git.repoDescribe r,
 	 		storeKey = store this,
 			retrieveKeyFile = retrieve this,
+			retrieveKeyFileCheap = retrieveCheap this,
 			removeKey = remove this,
 			hasKey = checkPresent this,
 			hasKeyCheap = False,
@@ -149,8 +150,8 @@ storeHelper (conn, bucket) r k file = do
 		xheaders = filter isxheader $ M.assocs $ fromJust $ config r
 		isxheader (h, _) = "x-amz-" `isPrefixOf` h
 
-retrieve :: Remote -> Key -> Bool -> FilePath -> Annex Bool
-retrieve r k _ f = s3Action r False $ \(conn, bucket) -> do
+retrieve :: Remote -> Key -> FilePath -> Annex Bool
+retrieve r k f = s3Action r False $ \(conn, bucket) -> do
 	res <- liftIO $ getObject conn $ bucketKey r bucket k
 	case res of
 		Right o -> do
@@ -158,6 +159,9 @@ retrieve r k _ f = s3Action r False $ \(conn, bucket) -> do
 			return True
 		Left e -> s3Warning e
 
+retrieveCheap :: Remote -> Key -> FilePath -> Annex Bool
+retrieveCheap _ _ _ = return False
+
 retrieveEncrypted :: Remote -> (Cipher, Key) -> FilePath -> Annex Bool
 retrieveEncrypted r (cipher, enck) f = s3Action r False $ \(conn, bucket) -> do
 	res <- liftIO $ getObject conn $ bucketKey r bucket enck

Remote/Web.hs

@@ -40,6 +40,7 @@ gen r _ _ =
 		name = Git.repoDescribe r,
 		storeKey = uploadKey,
 		retrieveKeyFile = downloadKey,
+		retrieveKeyFileCheap = downloadKeyCheap,
 		removeKey = dropKey,
 		hasKey = checkKey,
 		hasKeyCheap = False,
@@ -48,8 +49,8 @@ gen r _ _ =
 		remotetype = remote
 	}
 
-downloadKey :: Key -> Bool -> FilePath -> Annex Bool
-downloadKey key _ file = get =<< getUrls key
+downloadKey :: Key -> FilePath -> Annex Bool
+downloadKey key file = get =<< getUrls key
 	where
 		get [] = do
 			warning "no known url"
@@ -58,6 +59,9 @@ downloadKey key _ file = get =<< getUrls key
 			showOutput -- make way for download progress bar
 			downloadUrl urls file
 
+downloadKeyCheap :: Key -> FilePath -> Annex Bool
+downloadKeyCheap _ _ = return False
+
 uploadKey :: Key -> Annex Bool
 uploadKey _ = do
 	warning "upload to web not supported"

Types/Remote.hs

@@ -43,8 +43,10 @@ data RemoteA a = Remote {
 	cost :: Int,
 	-- Transfers a key to the remote.
 	storeKey :: Key -> a Bool,
-	-- retrieves a key's contents to a file (possibly a tmp file)
-	retrieveKeyFile :: Key -> Bool -> FilePath -> a Bool,
+	-- retrieves a key's contents to a file
+	retrieveKeyFile :: Key -> FilePath -> a Bool,
+	-- retrieves a key's contents to a tmp file, if it can be done cheaply
+	retrieveKeyFileCheap :: Key -> FilePath -> a Bool,
 	-- removes a key's contents
 	removeKey :: Key -> a Bool,
 	-- Checks if a key is present in the remote; if the remote

debian/changelog

@@ -8,6 +8,8 @@ git-annex (3.20120117) UNRELEASED; urgency=low
   * If you have any directory special remotes, now would be a good time to
     fsck them, in case you were hit by the data loss bug fixed in the
     previous release!
+  * fsck --from remote --fast: Avoids expensive file transfers, at the
+    expense of checking file size and/or contents.
 
  -- Joey Hess <joeyh@debian.org>  Thu, 19 Jan 2012 15:12:03 -0400
 

doc/git-annex.mdwn

@@ -210,10 +210,11 @@ subdirectories).
 
   With parameters, only the specified files are checked.
 
-  To avoid expensive checksum calculations, specify --fast
-
   To check a remote to fsck, specify --from.
   
+  To avoid expensive checksum calculations (and expensive transfers when
+  fscking a remote), specify --fast
+
 * unused
 
   Checks the annex for data that does not correspond to any files present