Merge branch 'forget'

Conflicts:
	debian/changelog

3 files changed, 220 insertions, 20 deletions

diff --git a/Annex/Branch.hs b/Annex/Branch.hs
index bc3736a9a..9ee281de9 100644
--- a/Annex/Branch.hs
+++ b/Annex/Branch.hs
@@ -1,6 +1,6 @@
 {- management of the git-annex branch
  -
- - Copyright 2011-2012 Joey Hess <joey@kitenet.net>
+ - Copyright 2011-2013 Joey Hess <joey@kitenet.net>
  -
  - Licensed under the GNU GPL version 3 or higher.
  -}
@@ -22,9 +22,12 @@ module Annex.Branch (
 	commit,
 	files,
 	withIndex,
+	performTransitions,
 ) where
 
 import qualified Data.ByteString.Lazy.Char8 as L
+import qualified Data.Set as S
+import qualified Data.Map as M
 
 import Common.Annex
 import Annex.BranchState
@@ -32,6 +35,7 @@ import Annex.Journal
 import qualified Git
 import qualified Git.Command
 import qualified Git.Ref
+import qualified Git.Sha
 import qualified Git.Branch
 import qualified Git.UnionMerge
 import qualified Git.UpdateIndex
@@ -42,6 +46,12 @@ import Annex.CatFile
 import Annex.Perms
 import qualified Annex
 import Utility.Env
+import Logs
+import Logs.Transitions
+import Logs.Trust.Pure
+import Annex.ReplaceFile
+import qualified Annex.Queue
+import Annex.Branch.Transitions
 
 {- Name of the branch that is used to store git-annex's information. -}
 name :: Git.Ref
@@ -110,6 +120,9 @@ forceUpdate = updateTo =<< siblingBranches
  - later get staged, and might overwrite changes made during the merge.
  - This is only done if some of the Refs do need to be merged.
  -
+ - Also handles performing any Transitions that have not yet been
+ - performed, in either the local branch, or the Refs.
+ -
  - Returns True if any refs were merged in, False otherwise.
  -}
 updateTo :: [(Git.Ref, Git.Branch)] -> Annex Bool
@@ -117,7 +130,8 @@ updateTo pairs = do
 	-- ensure branch exists, and get its current ref
 	branchref <- getBranch
 	dirty <- journalDirty
-	(refs, branches) <- unzip <$> filterM isnewer pairs
+	ignoredrefs <- getIgnoredRefs
+	(refs, branches) <- unzip <$> filterM (isnewer ignoredrefs) pairs
 	if null refs
 		{- Even when no refs need to be merged, the index
 		 - may still be updated if the branch has gotten ahead 
@@ -132,7 +146,9 @@ updateTo pairs = do
 		else lockJournal $ go branchref dirty refs branches
 	return $ not $ null refs
   where
-	isnewer (r, _) = inRepo $ Git.Branch.changed fullname r
+	isnewer ignoredrefs (r, _)
+		| S.member r ignoredrefs = return False
+		| otherwise = inRepo $ Git.Branch.changed fullname r
 	go branchref dirty refs branches = withIndex $ do
 		cleanjournal <- if dirty then stageJournal else return noop
 		let merge_desc = if null branches
@@ -140,23 +156,30 @@ updateTo pairs = do
 			else "merging " ++
 				unwords (map Git.Ref.describe branches) ++ 
 				" into " ++ show name
+		localtransitions <- parseTransitionsStrictly "local"
+			<$> getStale transitionsLog
 		unless (null branches) $ do
 			showSideAction merge_desc
 			mergeIndex refs
-		ff <- if dirty
-			then return False
-			else inRepo $ Git.Branch.fastForward fullname refs
-		if ff
-			then updateIndex branchref
-			else commitBranch branchref merge_desc
-				(nub $ fullname:refs)
+		let commitrefs = nub $ fullname:refs
+		transitioned <- handleTransitions localtransitions commitrefs
+		case transitioned of
+			Nothing -> do
+				ff <- if dirty
+					then return False
+					else inRepo $ Git.Branch.fastForward fullname refs
+				if ff
+					then updateIndex branchref
+					else commitBranch branchref merge_desc commitrefs
+			Just (branchref', commitrefs') ->
+				commitBranch branchref' merge_desc commitrefs'
 		liftIO cleanjournal
 
 {- Gets the content of a file, which may be in the journal, or in the index
  - (and committed to the branch).
  - 
  - Updates the branch if necessary, to ensure the most up-to-date available
- - content is available.
+ - content is returned.
  -
  - Returns an empty string if the file doesn't exist yet. -}
 get :: FilePath -> Annex String
@@ -175,7 +198,10 @@ get' :: FilePath -> Annex String
 get' file = go =<< getJournalFile file
   where
 	go (Just journalcontent) = return journalcontent
-	go Nothing = withIndex $ L.unpack <$> catFile fullname file
+	go Nothing = getRaw file
+	
+getRaw :: FilePath -> Annex String
+getRaw file = withIndex $ L.unpack <$> catFile fullname file
 
 {- Applies a function to modifiy the content of a file.
  -
@@ -253,13 +279,17 @@ commitBranch' branchref message parents = do
 files :: Annex [FilePath]
 files = do
 	update
-	withIndex $ do
-		bfiles <- inRepo $ Git.Command.pipeNullSplitZombie
-			[ Params "ls-tree --name-only -r -z"
-			, Param $ show fullname
-			]
-		jfiles <- getJournalledFiles
-		return $ jfiles ++ bfiles
+	(++)
+		<$> branchFiles
+		<*> getJournalledFiles
+
+{- Files in the branch, not including any from journalled changes,
+ - and without updating the branch. -}
+branchFiles :: Annex [FilePath]
+branchFiles = withIndex $ inRepo $ Git.Command.pipeNullSplitZombie
+	[ Params "ls-tree --name-only -r -z"
+	, Param $ show fullname
+	]
 
 {- Populates the branch's index file with the current branch contents.
  - 
@@ -361,3 +391,116 @@ stageJournal = withIndex $ do
 		sha <- hashFile h path
 		streamer $ Git.UpdateIndex.updateIndexLine
 			sha FileBlob (asTopFilePath $ fileJournal file)
+
+{- This is run after the refs have been merged into the index,
+ - but before the result is committed to the branch.
+ - Which is why it's passed the contents of the local branches's
+ - transition log before that merge took place.
+ -
+ - When the refs contain transitions that have not yet been done locally,
+ - the transitions are performed on the index, and a new branch
+ - is created from the result, and returned.
+ -
+ - When there are transitions recorded locally that have not been done
+ - to the remote refs, the transitions are performed in the index,
+ - and the existing branch is returned. In this case, the untransitioned
+ - remote refs cannot be merged into the branch (since transitions
+ - throw away history), so none of them are included in the returned
+ - list of refs, and they are added to the list of refs to ignore,
+ - to avoid re-merging content from them again.
+ -}
+handleTransitions :: Transitions -> [Git.Ref] -> Annex (Maybe (Git.Branch, [Git.Ref]))
+handleTransitions localts refs = do
+	m <- M.fromList <$> mapM getreftransition refs
+	let remotets = M.elems m
+	if all (localts ==) remotets
+		then return Nothing
+		else do
+			let allts = combineTransitions (localts:remotets)
+			let (transitionedrefs, untransitionedrefs) =
+				partition (\r -> M.lookup r m == Just allts) refs
+			transitionedbranch <- performTransitions allts (localts /= allts)
+			ignoreRefs untransitionedrefs
+			return $ Just (transitionedbranch, transitionedrefs)
+  where
+  	getreftransition ref = do
+		ts <- parseTransitionsStrictly "remote" . L.unpack
+			<$> catFile ref transitionsLog
+		return (ref, ts)
+
+ignoreRefs :: [Git.Ref] -> Annex ()
+ignoreRefs rs = do
+	old <- getIgnoredRefs
+	let s = S.unions [old, S.fromList rs]
+	f <- fromRepo gitAnnexIgnoredRefs
+	replaceFile f $ \tmp -> liftIO $ writeFile tmp $
+		unlines $ map show $ S.elems s
+
+getIgnoredRefs :: Annex (S.Set Git.Ref)
+getIgnoredRefs = S.fromList . mapMaybe Git.Sha.extractSha . lines <$> content
+  where
+  	content = do
+		f <- fromRepo gitAnnexIgnoredRefs
+		liftIO $ catchDefaultIO "" $ readFile f
+
+{- Performs the specified transitions on the contents of the index file,
+ - commits it to the branch, or creates a new branch, and returns 
+ - the branch's ref. -}
+performTransitions :: Transitions -> Bool -> Annex Git.Ref
+performTransitions ts neednewbranch = do
+	-- For simplicity & speed, we're going to use the Annex.Queue to
+	-- update the git-annex branch, while it usually holds changes
+	-- for the head branch. Flush any such changes.
+	Annex.Queue.flush
+	withIndex $ do
+		run $ mapMaybe getTransitionCalculator $ transitionList ts
+		Annex.Queue.flush
+		if neednewbranch
+			then do
+				committedref <- inRepo $ Git.Branch.commit message fullname []
+				setIndexSha committedref
+				return committedref
+			else do
+				ref <- getBranch
+				commitBranch ref message [fullname]
+				getBranch
+  where
+  	message
+		| neednewbranch = "new branch for transition " ++ tdesc
+		| otherwise = "continuing transition " ++ tdesc
+	tdesc = show $ map describeTransition $ transitionList ts
+
+	{- The changes to make to the branch are calculated and applied to
+	 - the branch directly, rather than going through the journal,
+	 - which would be innefficient. (And the journal is not designed
+	 - to hold changes to every file in the branch at once.)
+	 -
+	 - When a file in the branch is changed by transition code,
+	 - that value is remembered and fed into the code for subsequent
+	 - transitions.
+	 -}
+	run [] = noop
+	run changers = do
+		trustmap <- calcTrustMap <$> getRaw trustLog
+		fs <- branchFiles
+		hasher <- inRepo hashObjectStart
+		forM_ fs $ \f -> do
+			content <- getRaw f
+			apply changers hasher f content trustmap
+		liftIO $ hashObjectStop hasher
+	apply [] _ _ _ _ = return ()
+	apply (changer:rest) hasher file content trustmap =
+		case changer file content trustmap of
+			RemoveFile -> do
+				Annex.Queue.addUpdateIndex
+					=<< inRepo (Git.UpdateIndex.unstageFile file)
+				-- File is deleted; can't run any other
+				-- transitions on it.
+				return ()
+			ChangeFile content' -> do
+				sha <- inRepo $ hashObject BlobObject content'
+				Annex.Queue.addUpdateIndex $ Git.UpdateIndex.pureStreamer $
+					Git.UpdateIndex.updateIndexLine sha FileBlob (asTopFilePath file)
+				apply rest hasher file content' trustmap
+			PreserveFile ->
+				apply rest hasher file content trustmap
diff --git a/Annex/Branch/Transitions.hs b/Annex/Branch/Transitions.hs
new file mode 100644
index 000000000..90002de62
--- /dev/null
+++ b/Annex/Branch/Transitions.hs
@@ -0,0 +1,53 @@
+{- 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
diff --git a/Annex/TaggedPush.hs b/Annex/TaggedPush.hs
index 44a1a0eb0..039dc0e17 100644
--- a/Annex/TaggedPush.hs
+++ b/Annex/TaggedPush.hs
@@ -13,6 +13,7 @@ import qualified Annex.Branch
 import qualified Git
 import qualified Git.Ref
 import qualified Git.Command
+import qualified Git.Branch
 import Utility.Base64
 
 {- Converts a git branch into a branch that is tagged with a UUID, typically
@@ -50,7 +51,10 @@ taggedPush :: UUID -> Maybe String -> Git.Ref -> Remote -> Git.Repo -> IO Bool
 taggedPush u info branch remote = Git.Command.runBool
         [ Param "push"
         , Param $ Remote.name remote
-        , Param $ refspec Annex.Branch.name
+	{- Using forcePush here is safe because we "own" the tagged branch
+	 - we're pushing; it has no other writers. Ensures it is pushed
+	 - even if it has been rewritten by a transition. -}
+        , Param $ Git.Branch.forcePush $ refspec Annex.Branch.name
         , Param $ refspec branch
         ]
   where