git-annex/Command/Migrate.hs
Joey Hess c8e1e3dada
AssociatedFile newtype
To prevent any further mistakes like 301aff34c4

This commit was sponsored by Francois Marier on Patreon.
2017-03-10 13:35:31 -04:00

102 lines
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Haskell

{- git-annex command
-
- Copyright 2011 Joey Hess <id@joeyh.name>
-
- Licensed under the GNU GPL version 3 or higher.
-}
module Command.Migrate where
import Command
import Backend
import Types.Backend (canUpgradeKey, fastMigrate)
import Types.KeySource
import Annex.Content
import qualified Command.ReKey
import qualified Command.Fsck
import qualified Annex
import Logs.MetaData
import Logs.Web
import qualified Remote
cmd :: Command
cmd = notDirect $ withGlobalOptions annexedMatchingOptions $
command "migrate" SectionUtility
"switch data to different backend"
paramPaths (withParams seek)
seek :: CmdParams -> CommandSeek
seek = withFilesInGit $ whenAnnexed start
start :: FilePath -> Key -> CommandStart
start file key = do
forced <- Annex.getState Annex.force
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 || forced) && 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 (keySize key) || backendupgradable
where
backendupgradable = maybe False (\a -> a key) (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, knowngoodcontent))
| knowngoodcontent = finish newkey
| otherwise = stopUnless checkcontent $ finish newkey
checkcontent = Command.Fsck.checkBackend oldbackend oldkey Command.Fsck.KeyLocked afile
finish newkey = ifM (Command.ReKey.linkKey file oldkey newkey)
( do
copyMetaData oldkey newkey
-- If the old key had some associated urls, record them for
-- the new key as well.
urls <- getUrls oldkey
forM_ urls $ \url -> do
r <- Remote.claimingUrl url
setUrlPresent (Remote.uuid r) newkey url
next $ Command.ReKey.cleanup file oldkey newkey
, error "failed"
)
genkey = case maybe Nothing (\fm -> fm oldkey newbackend afile) (fastMigrate oldbackend) of
Just newkey -> return $ Just (newkey, True)
Nothing -> do
content <- calcRepo $ gitAnnexLocation oldkey
let source = KeySource
{ keyFilename = file
, contentLocation = content
, inodeCache = Nothing
}
v <- genKey source (Just newbackend)
return $ case v of
Just (newkey, _) -> Just (newkey, False)
_ -> Nothing
afile = AssociatedFile (Just file)