79 lines
2.4 KiB
Haskell
79 lines
2.4 KiB
Haskell
{- git-annex command
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-
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- Copyright 2011 Joey Hess <joey@kitenet.net>
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-
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- Licensed under the GNU GPL version 3 or higher.
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-}
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module Command.Migrate where
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import Common.Annex
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import Command
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import qualified Backend
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import qualified Types.Key
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import Annex.Content
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import qualified Command.Add
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import Logs.Web
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def :: [Command]
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def = [command "migrate" paramPaths seek "switch data to different backend"]
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seek :: [CommandSeek]
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seek = [withBackendFilesInGit $ \(b, f) -> whenAnnexed (start b) f]
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start :: Maybe (Backend Annex) -> FilePath -> (Key, Backend Annex) -> CommandStart
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start b file (key, oldbackend) = do
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exists <- inAnnex key
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newbackend <- choosebackend b
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if (newbackend /= oldbackend || upgradableKey key) && exists
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then do
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showStart "migrate" file
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next $ perform file key newbackend
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else stop
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where
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choosebackend Nothing = head <$> Backend.orderedList
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choosebackend (Just backend) = return backend
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{- Checks if a key is upgradable to a newer representation. -}
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{- Ideally, all keys have file size metadata. Old keys may not. -}
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upgradableKey :: Key -> Bool
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upgradableKey key = isNothing $ Types.Key.keySize key
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{- Store the old backend's key in the new backend
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- The old backend's key is not dropped from it, because there may
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- be other files still pointing at that key.
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-
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- Use the same filename as the file for the temp file name, to support
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- backends that allow the filename to influence the keys they
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- generate.
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-}
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perform :: FilePath -> Key -> Backend Annex -> CommandPerform
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perform file oldkey newbackend = do
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src <- inRepo $ gitAnnexLocation oldkey
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tmp <- fromRepo gitAnnexTmpDir
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let tmpfile = tmp </> takeFileName file
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cleantmp tmpfile
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liftIO $ createLink src tmpfile
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k <- Backend.genKey tmpfile $ Just newbackend
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cleantmp tmpfile
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case k of
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Nothing -> stop
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Just (newkey, _) -> stopUnless (link src newkey) $ do
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-- Update symlink to use the new key.
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liftIO $ removeFile file
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-- If the old key had some
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-- associated urls, record them for
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-- the new key as well.
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urls <- getUrls oldkey
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unless (null urls) $
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mapM_ (setUrlPresent newkey) urls
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next $ Command.Add.cleanup file newkey True
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where
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cleantmp t = liftIO $ whenM (doesFileExist t) $ removeFile t
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link src newkey = getViaTmpUnchecked newkey $ \t -> do
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-- Make a hard link to the old backend's
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-- cached key, to avoid wasting disk space.
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liftIO $ unlessM (doesFileExist t) $ createLink src t
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return True
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