git-annex/Command/Migrate.hs
Joey Hess e880d0d22c replace (Key, Backend) with Key
Only fsck and reinject and the test suite used the Backend, and they can
look it up as needed from the Key. This simplifies the code and also speeds
it up.

There is a small behavior change here. Before, all commands would warn when
acting on an annexed file with an unknown backend. Now, only fsck and
reinject show that warning.
2014-04-17 18:03:39 -04:00

81 lines
2.5 KiB
Haskell

{- 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 Backend
import qualified Types.Key
import qualified Types.Backend
import Types.KeySource
import Annex.Content
import qualified Command.ReKey
import qualified Command.Fsck
def :: [Command]
def = [notDirect $
command "migrate" paramPaths seek
SectionUtility "switch data to different backend"]
seek :: CommandSeek
seek = withFilesInGit $ whenAnnexed start
start :: FilePath -> Key -> CommandStart
start file key = do
v <- Backend.getBackend file key
case v of
Nothing -> stop
Just oldbackend -> do
exists <- inAnnex key
newbackend <- choosebackend =<< chooseBackend file
if (newbackend /= oldbackend || upgradableKey oldbackend key) && exists
then do
showStart "migrate" file
next $ perform file key oldbackend newbackend
else stop
where
choosebackend Nothing = Prelude.head <$> orderedList
choosebackend (Just backend) = return backend
{- Checks if a key is upgradable to a newer representation.
-
- Reasons for migration:
- - Ideally, all keys have file size metadata. Old keys may not.
- - Something has changed in the backend, such as a bug fix.
-}
upgradableKey :: Backend -> Key -> Bool
upgradableKey backend key = isNothing (Types.Key.keySize key) || backendupgradable
where
backendupgradable = maybe False (\a -> a key)
(Types.Backend.canUpgradeKey backend)
{- Store the old backend's key in the new backend
- The old backend's key is not dropped from it, because there may
- be other files still pointing at that key.
-
- To ensure that the data we have for the old key is valid, it's
- fscked here. First we generate the new key. This ensures that the
- data cannot get corrupted after the fsck but before the new key is
- generated.
-}
perform :: FilePath -> Key -> Backend -> Backend -> CommandPerform
perform file oldkey oldbackend newbackend = go =<< genkey
where
go Nothing = stop
go (Just newkey) = stopUnless checkcontent $ finish newkey
checkcontent = Command.Fsck.checkBackend oldbackend oldkey $ Just file
finish newkey = stopUnless (Command.ReKey.linkKey oldkey newkey) $
next $ Command.ReKey.cleanup file oldkey newkey
genkey = do
content <- calcRepo $ gitAnnexLocation oldkey
let source = KeySource
{ keyFilename = file
, contentLocation = content
, inodeCache = Nothing
}
liftM fst <$> genKey source (Just newbackend)