{- management of the git-annex branch - - Copyright 2011-2019 Joey Hess - - Licensed under the GNU AGPL version 3 or higher. -} module Annex.Branch ( fullname, name, hasOrigin, hasSibling, siblingBranches, create, update, forceUpdate, updateTo, get, getHistorical, change, maybeChange, commitMessage, commit, forceCommit, getBranch, files, rememberTreeish, performTransitions, withIndex, ) where import qualified Data.ByteString.Lazy as L import qualified Data.Set as S import qualified Data.Map as M import Data.Function import Data.Char import Data.ByteString.Builder import Control.Concurrent (threadDelay) import Annex.Common import Annex.BranchState import Annex.Journal import Annex.GitOverlay import Annex.Tmp import qualified Git import qualified Git.Command import qualified Git.Ref import qualified Git.RefLog import qualified Git.Sha import qualified Git.Branch import qualified Git.UnionMerge import qualified Git.UpdateIndex import qualified Git.Tree import qualified Git.LsTree import Git.LsTree (lsTreeParams) import qualified Git.HashObject import Annex.HashObject import Git.Types (Ref(..), fromRef, RefDate, TreeItemType(..)) import Git.FilePath import Annex.CatFile import Annex.Perms import Logs import Logs.Transitions import Logs.File import Logs.Trust.Pure import Logs.Remote.Pure import Logs.Difference.Pure import qualified Annex.Queue import Annex.Branch.Transitions import qualified Annex import Annex.Hook import Utility.Directory.Stream {- Name of the branch that is used to store git-annex's information. -} name :: Git.Ref name = Git.Ref "git-annex" {- Fully qualified name of the branch. -} fullname :: Git.Ref fullname = Git.Ref $ "refs/heads/" ++ fromRef name {- Branch's name in origin. -} originname :: Git.Ref originname = Git.Ref $ "origin/" ++ fromRef name {- Does origin/git-annex exist? -} hasOrigin :: Annex Bool hasOrigin = inRepo $ Git.Ref.exists originname {- Does the git-annex branch or a sibling foo/git-annex branch exist? -} hasSibling :: Annex Bool hasSibling = not . null <$> siblingBranches {- List of git-annex (shas, branches), including the main one and any - from remotes. Duplicates are filtered out. -} siblingBranches :: Annex [(Git.Sha, Git.Branch)] siblingBranches = inRepo $ Git.Ref.matchingUniq [name] {- Creates the branch, if it does not already exist. -} create :: Annex () create = void getBranch {- Returns the ref of the branch, creating it first if necessary. -} getBranch :: Annex Git.Ref getBranch = maybe (hasOrigin >>= go >>= use) return =<< branchsha where go True = do inRepo $ Git.Command.run [Param "branch", Param $ fromRef name, Param $ fromRef originname] fromMaybe (error $ "failed to create " ++ fromRef name) <$> branchsha go False = withIndex' True $ inRepo $ Git.Branch.commitAlways Git.Branch.AutomaticCommit "branch created" fullname [] use sha = do setIndexSha sha return sha branchsha = inRepo $ Git.Ref.sha fullname {- Ensures that the branch and index are up-to-date; should be - called before data is read from it. Runs only once per git-annex run. -} update :: Annex () update = runUpdateOnce $ void $ updateTo =<< siblingBranches {- Forces an update even if one has already been run. -} forceUpdate :: Annex Bool forceUpdate = updateTo =<< siblingBranches {- Merges the specified Refs into the index, if they have any changes not - already in it. The Branch names are only used in the commit message; - it's even possible that the provided Branches have not been updated to - point to the Refs yet. - - The branch is fast-forwarded if possible, otherwise a merge commit is - made. - - Before Refs are merged into the index, it's important to first stage the - journal into the index. Otherwise, any changes in the journal would - 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.Sha, Git.Branch)] -> Annex Bool updateTo pairs = ifM (annexMergeAnnexBranches <$> Annex.getGitConfig) ( updateTo' pairs , return False ) updateTo' :: [(Git.Sha, Git.Branch)] -> Annex Bool updateTo' pairs = do -- ensure branch exists, and get its current ref branchref <- getBranch dirty <- journalDirty ignoredrefs <- getIgnoredRefs let unignoredrefs = excludeset ignoredrefs pairs tomerge <- if null unignoredrefs then return [] else do mergedrefs <- getMergedRefs filterM isnewer (excludeset mergedrefs unignoredrefs) if null tomerge {- Even when no refs need to be merged, the index - may still be updated if the branch has gotten ahead - of the index. -} then do whenM (needUpdateIndex branchref) $ lockJournal $ \jl -> do forceUpdateIndex jl branchref {- When there are journalled changes - as well as the branch being updated, - a commit needs to be done. -} when dirty $ go branchref True [] jl else lockJournal $ go branchref dirty tomerge return $ not $ null tomerge where excludeset s = filter (\(r, _) -> S.notMember r s) isnewer (r, _) = inRepo $ Git.Branch.changed fullname r go branchref dirty tomerge jl = stagejournalwhen dirty jl $ do let (refs, branches) = unzip tomerge merge_desc <- if null tomerge then commitMessage else return $ "merging " ++ unwords (map Git.Ref.describe branches) ++ " into " ++ fromRef name localtransitions <- parseTransitionsStrictly "local" <$> getLocal transitionsLog unless (null tomerge) $ do showSideAction merge_desc mapM_ checkBranchDifferences refs mergeIndex jl refs let commitrefs = nub $ fullname:refs ifM (handleTransitions jl localtransitions commitrefs) ( runAnnexHook postUpdateAnnexHook , do ff <- if dirty then return False else inRepo $ Git.Branch.fastForward fullname refs if ff then updateIndex jl branchref else commitIndex jl branchref merge_desc commitrefs ) addMergedRefs tomerge stagejournalwhen dirty jl a | dirty = stageJournal jl a | otherwise = withIndex a {- 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 returned. - - Returns an empty string if the file doesn't exist yet. -} get :: FilePath -> Annex L.ByteString get file = do update getLocal file {- Like get, but does not merge the branch, so the info returned may not - reflect changes in remotes. - (Changing the value this returns, and then merging is always the - same as using get, and then changing its value.) -} getLocal :: FilePath -> Annex L.ByteString getLocal file = go =<< getJournalFileStale file where go (Just journalcontent) = return journalcontent go Nothing = getRef fullname file {- Gets the content of a file as staged in the branch's index. -} getStaged :: FilePath -> Annex L.ByteString getStaged = getRef indexref where -- This makes git cat-file be run with ":file", -- so it looks at the index. indexref = Ref "" getHistorical :: RefDate -> FilePath -> Annex L.ByteString getHistorical date file = -- This check avoids some ugly error messages when the reflog -- is empty. ifM (null <$> inRepo (Git.RefLog.get' [Param (fromRef fullname), Param "-n1"])) ( giveup ("No reflog for " ++ fromRef fullname) , getRef (Git.Ref.dateRef fullname date) file ) getRef :: Ref -> FilePath -> Annex L.ByteString getRef ref file = withIndex $ catFile ref file {- Applies a function to modify the content of a file. - - Note that this does not cause the branch to be merged, it only - modifes the current content of the file on the branch. -} change :: Journalable content => FilePath -> (L.ByteString -> content) -> Annex () change file f = lockJournal $ \jl -> f <$> getLocal file >>= set jl file {- Applies a function which can modify the content of a file, or not. -} maybeChange :: Journalable content => FilePath -> (L.ByteString -> Maybe content) -> Annex () maybeChange file f = lockJournal $ \jl -> do v <- getLocal file case f v of Just jv -> let b = journalableByteString jv in when (v /= b) $ set jl file b _ -> noop {- Records new content of a file into the journal -} set :: Journalable content => JournalLocked -> FilePath -> content -> Annex () set = setJournalFile {- Commit message used when making a commit of whatever data has changed - to the git-annex brach. -} commitMessage :: Annex String commitMessage = fromMaybe "update" . annexCommitMessage <$> Annex.getGitConfig {- Stages the journal, and commits staged changes to the branch. -} commit :: String -> Annex () commit = whenM journalDirty . forceCommit {- Commits the current index to the branch even without any journalled - changes. -} forceCommit :: String -> Annex () forceCommit message = lockJournal $ \jl -> stageJournal jl $ do ref <- getBranch commitIndex jl ref message [fullname] {- Commits the staged changes in the index to the branch. - - Ensures that the branch's index file is first updated to merge the state - of the branch at branchref, before running the commit action. This - is needed because the branch may have had changes pushed to it, that - are not yet reflected in the index. - - The branchref value can have been obtained using getBranch at any - previous point, though getting it a long time ago makes the race - more likely to occur. - - Note that changes may be pushed to the branch at any point in time! - So, there's a race. If the commit is made using the newly pushed tip of - the branch as its parent, and that ref has not yet been merged into the - index, then the result is that the commit will revert the pushed - changes, since they have not been merged into the index. This race - is detected and another commit made to fix it. - - (It's also possible for the branch to be overwritten, - losing the commit made here. But that's ok; the data is still in the - index and will get committed again later.) -} commitIndex :: JournalLocked -> Git.Ref -> String -> [Git.Ref] -> Annex () commitIndex jl branchref message parents = do showStoringStateAction commitIndex' jl branchref message message 0 parents commitIndex' :: JournalLocked -> Git.Ref -> String -> String -> Integer -> [Git.Ref] -> Annex () commitIndex' jl branchref message basemessage retrynum parents = do updateIndex jl branchref committedref <- inRepo $ Git.Branch.commitAlways Git.Branch.AutomaticCommit message fullname parents setIndexSha committedref parentrefs <- commitparents <$> catObject committedref when (racedetected branchref parentrefs) $ fixrace committedref parentrefs where -- look for "parent ref" lines and return the refs commitparents = map (Git.Ref . snd) . filter isparent . map (toassoc . decodeBL) . L.split newline newline = fromIntegral (ord '\n') toassoc = separate (== ' ') isparent (k,_) = k == "parent" {- The race can be detected by checking the commit's - parent, which will be the newly pushed branch, - instead of the expected ref that the index was updated to. -} racedetected expectedref parentrefs | expectedref `elem` parentrefs = False -- good parent | otherwise = True -- race! {- To recover from the race, union merge the lost refs - into the index. -} fixrace committedref lostrefs = do showSideAction "recovering from race" let retrynum' = retrynum+1 -- small sleep to let any activity that caused -- the race settle down liftIO $ threadDelay (100000 + fromInteger retrynum') mergeIndex jl lostrefs let racemessage = basemessage ++ " (recovery from race #" ++ show retrynum' ++ "; expected commit parent " ++ show branchref ++ " but found " ++ show lostrefs ++ " )" commitIndex' jl committedref racemessage basemessage retrynum' [committedref] {- Lists all files on the branch. including ones in the journal - that have not been committed yet. There may be duplicates in the list. -} files :: Annex [FilePath] files = do update -- ++ forces the content of the first list to be buffered in memory, -- so use getJournalledFilesStale which should be much smaller most -- of the time. branchFiles will stream as the list is consumed. (++) <$> getJournalledFilesStale <*> branchFiles {- Files in the branch, not including any from journalled changes, - and without updating the branch. -} branchFiles :: Annex [FilePath] branchFiles = withIndex $ inRepo branchFiles' branchFiles' :: Git.Repo -> IO [FilePath] branchFiles' = Git.Command.pipeNullSplitZombie (lsTreeParams Git.LsTree.LsTreeRecursive fullname [Param "--name-only"]) {- Populates the branch's index file with the current branch contents. - - This is only done when the index doesn't yet exist, and the index - is used to build up changes to be commited to the branch, and merge - in changes from other branches. -} genIndex :: Git.Repo -> IO () genIndex g = Git.UpdateIndex.streamUpdateIndex g [Git.UpdateIndex.lsTree fullname g] {- Merges the specified refs into the index. - Any changes staged in the index will be preserved. -} mergeIndex :: JournalLocked -> [Git.Ref] -> Annex () mergeIndex jl branches = do prepareModifyIndex jl hashhandle <- hashObjectHandle ch <- catFileHandle inRepo $ \g -> Git.UnionMerge.mergeIndex hashhandle ch g branches {- Removes any stale git lock file, to avoid git falling over when - updating the index. - - Since all modifications of the index are performed inside this module, - and only when the journal is locked, the fact that the journal has to be - locked when this is called ensures that no other process is currently - modifying the index. So any index.lock file must be stale, caused - by git running when the system crashed, or the repository's disk was - removed, etc. -} prepareModifyIndex :: JournalLocked -> Annex () prepareModifyIndex _jl = do index <- fromRepo gitAnnexIndex void $ liftIO $ tryIO $ removeFile $ index ++ ".lock" {- Runs an action using the branch's index file. -} withIndex :: Annex a -> Annex a withIndex = withIndex' False withIndex' :: Bool -> Annex a -> Annex a withIndex' bootstrapping a = do f <- fromRepo gitAnnexIndex withIndexFile f $ do checkIndexOnce $ unlessM (liftIO $ doesFileExist f) $ do unless bootstrapping create createAnnexDirectory $ takeDirectory f unless bootstrapping $ inRepo genIndex a {- Updates the branch's index to reflect the current contents of the branch. - Any changes staged in the index will be preserved. - - Compares the ref stored in the lock file with the current - ref of the branch to see if an update is needed. -} updateIndex :: JournalLocked -> Git.Ref -> Annex () updateIndex jl branchref = whenM (needUpdateIndex branchref) $ forceUpdateIndex jl branchref forceUpdateIndex :: JournalLocked -> Git.Ref -> Annex () forceUpdateIndex jl branchref = do withIndex $ mergeIndex jl [fullname] setIndexSha branchref {- Checks if the index needs to be updated. -} needUpdateIndex :: Git.Ref -> Annex Bool needUpdateIndex branchref = do f <- fromRepo gitAnnexIndexStatus committedref <- Git.Ref . firstLine <$> liftIO (catchDefaultIO "" $ readFileStrict f) return (committedref /= branchref) {- Record that the branch's index has been updated to correspond to a - given ref of the branch. -} setIndexSha :: Git.Ref -> Annex () setIndexSha ref = do f <- fromRepo gitAnnexIndexStatus writeLogFile f $ fromRef ref ++ "\n" runAnnexHook postUpdateAnnexHook {- Stages the journal into the index, and runs an action that - commits the index to the branch. Note that the action is run - inside withIndex so will automatically use the branch's index. - - Before staging, this removes any existing git index file lock. - This is safe to do because stageJournal is the only thing that - modifies this index file, and only one can run at a time, because - the journal is locked. So any existing git index file lock must be - stale, and the journal must contain any data that was in the process - of being written to the index file when it crashed. -} stageJournal :: JournalLocked -> Annex () -> Annex () stageJournal jl commitindex = withIndex $ withOtherTmp $ \tmpdir -> do prepareModifyIndex jl g <- gitRepo let dir = gitAnnexJournalDir g (jlogf, jlogh) <- openjlog tmpdir h <- hashObjectHandle withJournalHandle $ \jh -> Git.UpdateIndex.streamUpdateIndex g [genstream dir h jh jlogh] commitindex liftIO $ cleanup dir jlogh jlogf where genstream dir h jh jlogh streamer = readDirectory jh >>= \case Nothing -> return () Just file -> do unless (dirCruft file) $ do let path = dir file sha <- Git.HashObject.hashFile h path hPutStrLn jlogh file streamer $ Git.UpdateIndex.updateIndexLine sha TreeFile (asTopFilePath $ fileJournal file) genstream dir h jh jlogh streamer -- Clean up the staged files, as listed in the temp log file. -- The temp file is used to avoid needing to buffer all the -- filenames in memory. cleanup dir jlogh jlogf = do hFlush jlogh hSeek jlogh AbsoluteSeek 0 stagedfs <- lines <$> hGetContents jlogh mapM_ (removeFile . (dir )) stagedfs hClose jlogh nukeFile jlogf openjlog tmpdir = liftIO $ openTempFile tmpdir "jlog" {- 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. - - When there are transitions recorded locally that have not been done - to the remote refs, the transitions are performed in the index, - and committed to the existing branch. In this case, the untransitioned - remote refs cannot be merged into the branch (since transitions - throw away history), so they are added to the list of refs to ignore, - to avoid re-merging content from them again. -} handleTransitions :: JournalLocked -> Transitions -> [Git.Ref] -> Annex Bool handleTransitions jl localts refs = do m <- M.fromList <$> mapM getreftransition refs let remotets = M.elems m if all (localts ==) remotets then return False else do let allts = combineTransitions (localts:remotets) let (transitionedrefs, untransitionedrefs) = partition (\r -> M.lookup r m == Just allts) refs performTransitionsLocked jl allts (localts /= allts) transitionedrefs ignoreRefs untransitionedrefs return True where getreftransition ref = do ts <- parseTransitionsStrictly "remote" <$> catFile ref transitionsLog return (ref, ts) {- Performs the specified transitions on the contents of the index file, - commits it to the branch, or creates a new branch. -} performTransitions :: Transitions -> Bool -> [Ref] -> Annex () performTransitions ts neednewlocalbranch transitionedrefs = lockJournal $ \jl -> performTransitionsLocked jl ts neednewlocalbranch transitionedrefs performTransitionsLocked :: JournalLocked -> Transitions -> Bool -> [Ref] -> Annex () performTransitionsLocked jl ts neednewlocalbranch transitionedrefs = 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 -- Stop any running git cat-files, to ensure that the -- getStaged calls below use the current index, and not some older -- one. catFileStop withIndex $ do prepareModifyIndex jl run $ mapMaybe getTransitionCalculator tlist Annex.Queue.flush if neednewlocalbranch then do committedref <- inRepo $ Git.Branch.commitAlways Git.Branch.AutomaticCommit message fullname transitionedrefs setIndexSha committedref else do ref <- getBranch commitIndex jl ref message (nub $ fullname:transitionedrefs) where message | neednewlocalbranch && null transitionedrefs = "new branch for transition " ++ tdesc | otherwise = "continuing transition " ++ tdesc tdesc = show $ map describeTransition tlist tlist = knownTransitionList 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, - its new content is remembered and fed into the code for subsequent - transitions. -} run [] = noop run changers = do trustmap <- calcTrustMap <$> getStaged trustLog remoteconfigmap <- calcRemoteConfigMap <$> getStaged remoteLog -- partially apply, improves performance let changers' = map (\c -> c trustmap remoteconfigmap) changers fs <- branchFiles forM_ fs $ \f -> do content <- getStaged f apply changers' f content apply [] _ _ = return () apply (changer:rest) file content = case changer file content of PreserveFile -> apply rest file content ChangeFile builder -> do let content' = toLazyByteString builder if L.null content' then do Annex.Queue.addUpdateIndex =<< inRepo (Git.UpdateIndex.unstageFile file) -- File is deleted; can't run any other -- transitions on it. return () else do sha <- hashBlob content' Annex.Queue.addUpdateIndex $ Git.UpdateIndex.pureStreamer $ Git.UpdateIndex.updateIndexLine sha TreeFile (asTopFilePath file) apply rest file content' checkBranchDifferences :: Git.Ref -> Annex () checkBranchDifferences ref = do theirdiffs <- allDifferences . parseDifferencesLog <$> catFile ref differenceLog mydiffs <- annexDifferences <$> Annex.getGitConfig when (theirdiffs /= mydiffs) $ giveup "Remote repository is tuned in incompatible way; cannot be merged with local repository." ignoreRefs :: [Git.Sha] -> Annex () ignoreRefs rs = do old <- getIgnoredRefs let s = S.unions [old, S.fromList rs] f <- fromRepo gitAnnexIgnoredRefs writeLogFile f $ unlines $ map fromRef $ S.elems s getIgnoredRefs :: Annex (S.Set Git.Sha) getIgnoredRefs = S.fromList . mapMaybe Git.Sha.extractSha . lines <$> content where content = do f <- fromRepo gitAnnexIgnoredRefs liftIO $ catchDefaultIO "" $ readFile f addMergedRefs :: [(Git.Sha, Git.Branch)] -> Annex () addMergedRefs [] = return () addMergedRefs new = do old <- getMergedRefs' -- Keep only the newest sha for each branch. let l = nubBy ((==) `on` snd) (new ++ old) f <- fromRepo gitAnnexMergedRefs writeLogFile f $ unlines $ map (\(s, b) -> fromRef s ++ '\t' : fromRef b) l getMergedRefs :: Annex (S.Set Git.Sha) getMergedRefs = S.fromList . map fst <$> getMergedRefs' getMergedRefs' :: Annex [(Git.Sha, Git.Branch)] getMergedRefs' = do f <- fromRepo gitAnnexMergedRefs s <- liftIO $ catchDefaultIO "" $ readFile f return $ map parse $ lines s where parse l = let (s, b) = separate (== '\t') l in (Ref s, Ref b) {- Grafts a treeish into the branch at the specified location, - and then removes it. This ensures that the treeish won't get garbage - collected, and will always be available as long as the git-annex branch - is available. -} rememberTreeish :: Git.Ref -> TopFilePath -> Annex () rememberTreeish treeish graftpoint = lockJournal $ \jl -> do branchref <- getBranch updateIndex jl branchref origtree <- fromMaybe (giveup "unable to determine git-annex branch tree") <$> inRepo (Git.Ref.tree branchref) addedt <- inRepo $ Git.Tree.graftTree treeish graftpoint origtree c <- inRepo $ Git.Branch.commitTree Git.Branch.AutomaticCommit "graft" [branchref] addedt c' <- inRepo $ Git.Branch.commitTree Git.Branch.AutomaticCommit "graft cleanup" [c] origtree inRepo $ Git.Branch.update' fullname c' -- The tree in c' is the same as the tree in branchref, -- and the index was updated to that above, so it's safe to -- say that the index contains c'. setIndexSha c'