git-annex/Command/ReKey.hs
Joey Hess 34c8af74ba fix inversion of control in CommandSeek (no behavior changes)
I've been disliking how the command seek actions were written for some
time, with their inversion of control and ugly workarounds.

The last straw to fix it was sync --content, which didn't fit the
Annex [CommandStart] interface well at all. I have not yet made it take
advantage of the changed interface though.

The crucial change, and probably why I didn't do it this way from the
beginning, is to make each CommandStart action be run with exceptions
caught, and if it fails, increment a failure counter in annex state.
So I finally remove the very first code I wrote for git-annex, which
was before I had exception handling in the Annex monad, and so ran outside
that monad, passing state explicitly as it ran each CommandStart action.

This was a real slog from 1 to 5 am.

Test suite passes.

Memory usage is lower than before, sometimes by a couple of megabytes, and
remains constant, even when running in a large repo, and even when
repeatedly failing and incrementing the error counter. So no accidental
laziness space leaks.

Wall clock speed is identical, even in large repos.

This commit was sponsored by an anonymous bitcoiner.
2014-01-20 04:57:36 -04:00

71 lines
1.8 KiB
Haskell

{- git-annex command
-
- Copyright 2012 Joey Hess <joey@kitenet.net>
-
- Licensed under the GNU GPL version 3 or higher.
-}
module Command.ReKey where
import Common.Annex
import Command
import qualified Annex
import Types.Key
import Annex.Content
import qualified Command.Add
import Logs.Web
import Logs.Location
import Utility.CopyFile
def :: [Command]
def = [notDirect $ command "rekey"
(paramOptional $ paramRepeating $ paramPair paramPath paramKey)
seek SectionPlumbing "change keys used for files"]
seek :: CommandSeek
seek = withPairs start
start :: (FilePath, String) -> CommandStart
start (file, keyname) = ifAnnexed file go stop
where
newkey = fromMaybe (error "bad key") $ file2key keyname
go (oldkey, _)
| oldkey == newkey = stop
| otherwise = do
showStart "rekey" file
next $ perform file oldkey newkey
perform :: FilePath -> Key -> Key -> CommandPerform
perform file oldkey newkey = do
present <- inAnnex oldkey
_ <- if present
then linkKey oldkey newkey
else do
unlessM (Annex.getState Annex.force) $
error $ file ++ " is not available (use --force to override)"
return True
next $ cleanup file oldkey newkey
{- Make a hard link to the old key content (when supported),
- to avoid wasting disk space. -}
linkKey :: Key -> Key -> Annex Bool
linkKey oldkey newkey = getViaTmpUnchecked newkey $ \tmp -> do
src <- calcRepo $ gitAnnexLocation oldkey
liftIO $ ifM (doesFileExist tmp)
( return True
, createLinkOrCopy src tmp
)
cleanup :: FilePath -> Key -> Key -> CommandCleanup
cleanup file oldkey newkey = do
-- If the old key had some associated urls, record them for
-- the new key as well.
urls <- getUrls oldkey
unless (null urls) $
mapM_ (setUrlPresent newkey) urls
-- Update symlink to use the new key.
liftIO $ removeFile file
Command.Add.addLink file newkey Nothing
logStatus newkey InfoPresent
return True