git-annex/Command/Migrate.hs
Joey Hess b223988e22
remove --backend from global options
--backend is no longer a global option, and is only accepted by commands
that actually need it.

Three commands that used to support backend but don't any longer are
watch, webapp, and assistant. It would be possible to make them support it,
but I doubt anyone used the option with these. And in the case of webapp
and assistant, the option was handled inconsistently, only taking affect
when the command is run with an existing git-annex repo, not when it
creates a new one.

Also, renamed GlobalOption etc to AnnexOption. Because there are many
options of this type that are not actually global (any more) and get
added to commands that need them.

Sponsored-by: Kevin Mueller on Patreon
2022-06-29 13:33:25 -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 = withAnnexOptions [backendOption, 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.getRead 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 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)