git-annex/Command/Migrate.hs
Joey Hess 51b73ea1fc
migrate: New --remove-size option
While intended for converting URL keys added by addurl --fast to be
as if added by addurl --relaxed, it can also be used to remove size
from other types of keys. Although that is not likely to be useful
for checksummed keys, I suppose it could be used for WORM or other
non-checksum keys.

Specifying the --remove-size option does not prevent other migrations
from taking effect if there's a key upgrade to perform, or if the
backend has changed. So --backend=URL needs to be used to prevent
migrating an URL key to the default backend.

Note that it's not possible to use git-annex migrate to convert from a
non-URL key to an URL key, as URL keys cannot be generated, except by
addurl. So while this can get the same effect as --relaxed would have
when addurl --fast was used, when --fast was not used, it won't work, or
if --backend=URL is not used will remove the size but not prevent
checksum verification, which is not useful. Due to this complexity, I
decided not to mention it in the git-annex addurl man page.

Sponsored-by: Jochen Bartl on Patreon
2021-11-12 13:28:28 -04:00

127 lines
4 KiB
Haskell

{- git-annex command
-
- Copyright 2011 Joey Hess <id@joeyh.name>
-
- Licensed under the GNU AGPL 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 Utility.Metered
cmd :: Command
cmd = withGlobalOptions [annexedMatchingOptions] $
command "migrate" SectionUtility
"switch data to different backend"
paramPaths (seek <$$> optParser)
data MigrateOptions = MigrateOptions
{ migrateThese :: CmdParams
, removeSize :: Bool
}
optParser :: CmdParamsDesc -> Parser MigrateOptions
optParser desc = MigrateOptions
<$> cmdParams desc
<*> switch
( long "remove-size"
<> help "remove size field from keys"
)
seek :: MigrateOptions -> CommandSeek
seek o = withFilesInGitAnnex ww seeker =<< workTreeItems ww (migrateThese o)
where
ww = WarnUnmatchLsFiles
seeker = AnnexedFileSeeker
{ startAction = start o
, checkContentPresent = Nothing
, usesLocationLog = False
}
start :: MigrateOptions -> SeekInput -> RawFilePath -> Key -> CommandStart
start o si file key = do
forced <- Annex.getState Annex.force
v <- Backend.getBackend (fromRawFilePath file) key
case v of
Nothing -> stop
Just oldbackend -> do
exists <- inAnnex key
newbackend <- maybe defaultBackend return
=<< chooseBackend file
if (newbackend /= oldbackend || upgradableKey oldbackend key || forced) && exists
then go False oldbackend newbackend
else if removeSize o && exists
then go True oldbackend oldbackend
else stop
where
go onlyremovesize oldbackend newbackend =
starting "migrate" (mkActionItem (key, file)) si $
perform onlyremovesize o file key oldbackend newbackend
{- 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 (fromKey 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 :: Bool -> MigrateOptions -> RawFilePath -> Key -> Backend -> Backend -> CommandPerform
perform onlyremovesize o file oldkey oldbackend newbackend = go =<< genkey (fastMigrate oldbackend)
where
go Nothing = stop
go (Just (newkey, knowngoodcontent))
| knowngoodcontent = finish (removesize newkey)
| otherwise = stopUnless checkcontent $
finish (removesize newkey)
checkcontent = Command.Fsck.checkBackend oldbackend oldkey Command.Fsck.KeyPresent 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 ->
setUrlPresent newkey url
next $ Command.ReKey.cleanup file newkey
, giveup "failed creating link from old to new key"
)
genkey _ | onlyremovesize = return $ Just (oldkey, False)
genkey Nothing = do
content <- calcRepo $ gitAnnexLocation oldkey
let source = KeySource
{ keyFilename = file
, contentLocation = content
, inodeCache = Nothing
}
newkey <- fst <$> genKey source nullMeterUpdate (Just newbackend)
return $ Just (newkey, False)
genkey (Just fm) = fm oldkey newbackend afile >>= \case
Just newkey -> return (Just (newkey, True))
Nothing -> genkey Nothing
removesize k
| removeSize o = alterKey k $ \kd -> kd { keySize = Nothing }
| otherwise = k
afile = AssociatedFile (Just file)