git-annex/Command/Migrate.hs
Joey Hess 3a05d53761
add SeekInput (not yet used)
No behavior changes (hopefully), just adding SeekInput and plumbing it
through to the JSON display code for later use.

Over the course of 2 grueling days.

withFilesNotInGit reimplemented in terms of seekHelper
should be the only possible behavior change. It seems to test as
behaving the same.

Note that seekHelper dummies up the SeekInput in the case where
segmentPaths' gives up on sorting the expanded paths because there are
too many input paths. When SeekInput later gets exposed as a json field,
that will result in it being a little bit wrong in the case where
100 or more paths are passed to a git-annex command. I think this is a
subtle enough problem to not matter. If it does turn out to be a
problem, fixing it would require splitting up the input
parameters into groups of < 100, which would make git ls-files run
perhaps more than is necessary. May want to revisit this, because that
fix seems fairly low-impact.
2020-09-15 15:41:13 -04:00

104 lines
3.3 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 (withParams seek)
seek :: CmdParams -> CommandSeek
seek = withFilesInGitAnnex ww seeker <=< workTreeItems ww
where
ww = WarnUnmatchLsFiles
seeker = AnnexedFileSeeker
{ startAction = start
, checkContentPresent = Nothing
, usesLocationLog = False
}
start :: SeekInput -> RawFilePath -> Key -> CommandStart
start 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 (fromRawFilePath file)
if (newbackend /= oldbackend || upgradableKey oldbackend key || forced) && exists
then starting "migrate" (mkActionItem (key, file)) si $
perform file key oldbackend newbackend
else stop
{- 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 :: RawFilePath -> Key -> Backend -> Backend -> CommandPerform
perform file oldkey oldbackend newbackend = go =<< genkey (fastMigrate oldbackend)
where
go Nothing = stop
go (Just (newkey, knowngoodcontent))
| knowngoodcontent = finish newkey
| otherwise = stopUnless checkcontent $ finish 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 oldkey newkey
, giveup "failed creating link from old to new key"
)
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
afile = AssociatedFile (Just file)