git-annex/Annex/Drop.hs
2015-04-30 14:02:56 -04:00

123 lines
3.7 KiB
Haskell

{- dropping of unwanted content
-
- Copyright 2012-2014 Joey Hess <id@joeyh.name>
-
- Licensed under the GNU GPL version 3 or higher.
-}
module Annex.Drop where
import Common.Annex
import Logs.Trust
import Annex.NumCopies
import Types.Remote (uuid)
import Types.Key (key2file)
import qualified Remote
import qualified Command.Drop
import Command
import Annex.Wanted
import Config
import Annex.Content.Direct
import qualified Data.Set as S
import System.Log.Logger (debugM)
type Reason = String
{- Drop a key from local and/or remote when allowed by the preferred content
- and numcopies settings.
-
- The UUIDs are ones where the content is believed to be present.
- The Remote list can include other remotes that do not have the content;
- only ones that match the UUIDs will be dropped from.
- If allowed to drop fromhere, that drop will be tried first.
-
- A remote can be specified that is known to have the key. This can be
- used an an optimisation when eg, a key has just been uploaded to a
- remote.
-
- In direct mode, all associated files are checked, and only if all
- of them are unwanted are they dropped.
-
- The runner is used to run commands, and so can be either callCommand
- or commandAction.
-}
handleDropsFrom :: [UUID] -> [Remote] -> Reason -> Bool -> Key -> AssociatedFile -> Maybe Remote -> CommandActionRunner -> Annex ()
handleDropsFrom locs rs reason fromhere key afile knownpresentremote runner = do
fs <- ifM isDirect
( do
l <- associatedFilesRelative key
return $ if null l
then maybeToList afile
else l
, return $ maybeToList afile
)
n <- getcopies fs
if fromhere && checkcopies n Nothing
then go fs rs =<< dropl fs n
else go fs rs n
where
getcopies fs = do
(untrusted, have) <- trustPartition UnTrusted locs
numcopies <- if null fs
then getNumCopies
else maximum <$> mapM getFileNumCopies fs
return (NumCopies (length have), numcopies, S.fromList untrusted)
{- Check that we have enough copies still to drop the content.
- When the remote being dropped from is untrusted, it was not
- counted as a copy, so having only numcopies suffices. Otherwise,
- we need more than numcopies to safely drop. -}
checkcopies (have, numcopies, _untrusted) Nothing = have > numcopies
checkcopies (have, numcopies, untrusted) (Just u)
| S.member u untrusted = have >= numcopies
| otherwise = have > numcopies
decrcopies (have, numcopies, untrusted) Nothing =
(NumCopies (fromNumCopies have - 1), numcopies, untrusted)
decrcopies v@(_have, _numcopies, untrusted) (Just u)
| S.member u untrusted = v
| otherwise = decrcopies v Nothing
go _ [] _ = noop
go fs (r:rest) n
| uuid r `S.notMember` slocs = go fs rest n
| checkcopies n (Just $ Remote.uuid r) =
dropr fs r n >>= go fs rest
| otherwise = noop
checkdrop fs n u a
| null fs = check $ -- no associated files; unused content
wantDrop True u (Just key) Nothing
| otherwise = check $
allM (wantDrop True u (Just key) . Just) fs
where
check c = ifM c
( dodrop n u a
, return n
)
dodrop n@(have, numcopies, _untrusted) u a =
ifM (safely $ runner $ a numcopies)
( do
liftIO $ debugM "drop" $ unwords
[ "dropped"
, fromMaybe (key2file key) afile
, "(from " ++ maybe "here" show u ++ ")"
, "(copies now " ++ show (fromNumCopies have - 1) ++ ")"
, ": " ++ reason
]
return $ decrcopies n u
, return n
)
dropl fs n = checkdrop fs n Nothing $ \numcopies ->
Command.Drop.startLocal afile numcopies key knownpresentremote
dropr fs r n = checkdrop fs n (Just $ Remote.uuid r) $ \numcopies ->
Command.Drop.startRemote afile numcopies key r
slocs = S.fromList locs
safely a = either (const False) id <$> tryNonAsync a