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{- git-annex command
-
- Copyright 2011 Joey Hess <joey@kitenet.net>
-
- Licensed under the GNU GPL version 3 or higher.
-}
module Command.Migrate where
import Common.Annex
import Command
import qualified Backend
import qualified Types.Key
import Annex.Content
import qualified Command.Add
import Logs.Web
def :: [Command]
def = [command "migrate" paramPaths seek "switch data to different backend"]
seek :: [CommandSeek]
seek = [withBackendFilesInGit $ \(b, f) -> whenAnnexed (start b) f]
start :: Maybe (Backend Annex) -> FilePath -> (Key, Backend Annex) -> CommandStart
start b file (key, oldbackend) = do
exists <- inAnnex key
newbackend <- choosebackend b
if (newbackend /= oldbackend || upgradableKey key) && exists
then do
showStart "migrate" file
next $ perform file key newbackend
else stop
where
choosebackend Nothing = head <$> Backend.orderedList
choosebackend (Just backend) = return backend
{- Checks if a key is upgradable to a newer representation. -}
{- Ideally, all keys have file size metadata. Old keys may not. -}
upgradableKey :: Key -> Bool
upgradableKey key = isNothing $ Types.Key.keySize key
perform :: FilePath -> Key -> Backend Annex -> CommandPerform
perform file oldkey newbackend = do
-- Store the old backend's cached key in the new backend
-- (the file can't be stored as usual, because it's already a symlink).
-- The old backend's key is not dropped from it, because there may
-- be other files still pointing at that key.
src <- fromRepo $ gitAnnexLocation oldkey
tmp <- fromRepo gitAnnexTmpDir
let tmpfile = tmp </> takeFileName file
cleantmp tmpfile
liftIO $ createLink src tmpfile
k <- Backend.genKey tmpfile $ Just newbackend
cleantmp tmpfile
case k of
Nothing -> stop
Just (newkey, _) -> do
ok <- link src newkey
if ok
then do
-- Update symlink to use the new key.
liftIO $ removeFile file
-- If the old key had some
-- associated urls, record them for
-- the new key as well.
urls <- getUrls oldkey
unless (null urls) $
mapM_ (setUrlPresent newkey) urls
next $ Command.Add.cleanup file newkey True
else stop
where
cleantmp t = liftIO $ whenM (doesFileExist t) $ removeFile t
link src newkey = getViaTmpUnchecked newkey $ \t -> do
-- Make a hard link to the old backend's
-- cached key, to avoid wasting disk space.
liftIO $ unlessM (doesFileExist t) $ createLink src t
return True
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