git-annex/Annex/Branch/Transitions.hs
Joey Hess 0831e18372 forget --drop-dead: Completely removes mentions of repositories that have been marked as dead from the git-annex branch.
Wrote nice pure transition calculator, and ugly code to stage its results
into the git-annex branch. Also had to split up several Log modules
that Annex.Branch needed to use, but that themselves used Annex.Branch.

The transition calculator is limited to looking at and changing one file at
a time. While this made the implementation relatively easy, it precludes
transitions that do stuff like deleting old url log files for keys that are
being removed because they are no longer present anywhere.
2013-08-31 17:51:13 -04:00

53 lines
1.8 KiB
Haskell

{- git-annex branch transitions
-
- Copyright 2013 Joey Hess <joey@kitenet.net>
-
- Licensed under the GNU GPL version 3 or higher.
-}
module Annex.Branch.Transitions (
FileTransition(..),
getTransitionCalculator
) where
import Logs
import Logs.Transitions
import Logs.UUIDBased as UUIDBased
import Logs.Presence.Pure as Presence
import Types.TrustLevel
import Types.UUID
import qualified Data.Map as M
data FileTransition
= ChangeFile String
| RemoveFile
| PreserveFile
type TransitionCalculator = FilePath -> String -> TrustMap -> FileTransition
getTransitionCalculator :: Transition -> Maybe TransitionCalculator
getTransitionCalculator ForgetGitHistory = Nothing
getTransitionCalculator ForgetDeadRemotes = Just dropDead
dropDead :: FilePath -> String -> TrustMap -> FileTransition
dropDead f content trustmap = case getLogVariety f of
Just UUIDBasedLog -> ChangeFile $
UUIDBased.showLog id $ dropDeadFromUUIDBasedLog trustmap $ UUIDBased.parseLog Just content
Just (PresenceLog _) ->
let newlog = Presence.compactLog $ dropDeadFromPresenceLog trustmap $ Presence.parseLog content
in if null newlog
then RemoveFile
else ChangeFile $ Presence.showLog newlog
Nothing -> PreserveFile
dropDeadFromUUIDBasedLog :: TrustMap -> UUIDBased.Log String -> UUIDBased.Log String
dropDeadFromUUIDBasedLog trustmap = M.filterWithKey $ notDead trustmap . const
{- Presence logs can contain UUIDs or other values. Any line that matches
- a dead uuid is dropped; any other values are passed through. -}
dropDeadFromPresenceLog :: TrustMap -> [Presence.LogLine] -> [Presence.LogLine]
dropDeadFromPresenceLog trustmap = filter $ notDead trustmap (toUUID . Presence.info)
notDead :: TrustMap -> (v -> UUID) -> v -> Bool
notDead trustmap a v = M.findWithDefault SemiTrusted (a v) trustmap /= DeadTrusted