From 7a693394f4acd05d1dedbaffec0762007a954d9e Mon Sep 17 00:00:00 2001 From: Joey Hess Date: Tue, 21 Jun 2011 19:52:40 -0400 Subject: [PATCH] allow for union merges between a tree and the content in the index This is needed for robust handling of the git-annex branch. Since changes are staged to its index as git-annex runs, and committed at the end, it's possible that git-annex is interrupted, and leaves a dirty index. When it next runs, it needs to be able to merge the git-annex branch as necessary, without losing the existing changes in the index. Note that this assumes that the git-annex branch is only modified by git-annex. Any changes to it will be lost when git-annex updates the branch. I don't see a good, inexpensive way to find changes in the git-annex branch that arn't in the index, and union merging the git-annex branch into the index every time would likewise be expensive. --- Branch.hs | 31 ++++++++++++------ GitUnionMerge.hs | 79 +++++++++++++++++++++++++++------------------- git-union-merge.hs | 3 +- 3 files changed, 70 insertions(+), 43 deletions(-) diff --git a/Branch.hs b/Branch.hs index 82ff5fcad7..9d7b1b0941 100644 --- a/Branch.hs +++ b/Branch.hs @@ -12,12 +12,13 @@ module Branch ( commit ) where -import Control.Monad (unless) +import Control.Monad (unless, liftM) import Control.Monad.State (liftIO) import System.FilePath import System.Directory import Data.String.Utils import System.Cmd.Utils +import Data.Maybe import qualified GitRepo as Git import qualified GitUnionMerge @@ -72,14 +73,18 @@ update = do updated <- Annex.getState Annex.updated unless updated $ withIndex $ do g <- Annex.gitRepo - refs <- liftIO $ Git.pipeRead g [Param "show-ref", Param name] - mapM_ updateRef $ map (last . words) (lines refs) + r <- liftIO $ Git.pipeRead g [Param "show-ref", Param name] + let refs = map (last . words) (lines r) + updated <- catMaybes `liftM` mapM updateRef refs + unless (null updated) $ liftIO $ + GitUnionMerge.commit g "update" fullname + (fullname:updated) Annex.changeState $ \s -> s { Annex.updated = True } -{- Ensures that a given ref has been merged into the local git-annex branch. -} -updateRef :: String -> Annex () +{- Ensures that a given ref has been merged into the index. -} +updateRef :: String -> Annex (Maybe String) updateRef ref - | ref == fullname = return () + | ref == fullname = return Nothing | otherwise = do g <- Annex.gitRepo diffs <- liftIO $ Git.pipeRead g [ @@ -87,9 +92,15 @@ updateRef ref Param (name++".."++ref), Params "--oneline -n1" ] - unless (null diffs) $ do - showSideAction $ "merging " ++ ref ++ " into " ++ name ++ "..." - liftIO $ unionMerge g fullname ref fullname True + if (null diffs) + then return Nothing + else do + showSideAction $ "merging " ++ ref ++ " into " ++ name ++ "..." + -- By passing only one ref, it is actually + -- merged into the index, preserving any + -- changes that may already be staged. + liftIO $ GitUnionMerge.merge g [ref] + return $ Just ref {- Stages the content of a file into the branch's index. -} change :: FilePath -> String -> Annex () @@ -104,7 +115,7 @@ change file content = do commit :: String -> Annex () commit message = withIndex $ do g <- Annex.gitRepo - liftIO $ GitUnionMerge.commit g message branch [] + liftIO $ GitUnionMerge.commit g message fullname [] {- Gets the content of a file on the branch, or content staged in the index - if it's newer. Returns an empty string if the file didn't exist yet. -} diff --git a/GitUnionMerge.hs b/GitUnionMerge.hs index bc12cbe275..82f01cc0ff 100644 --- a/GitUnionMerge.hs +++ b/GitUnionMerge.hs @@ -7,7 +7,6 @@ module GitUnionMerge ( merge, - stage, commit ) where @@ -19,38 +18,54 @@ import Data.String.Utils import qualified GitRepo as Git import Utility -{- Performs a union merge. Should be run with a temporary index file - - configured by Git.useIndex. +{- Performs a union merge between two branches, staging it in the index. + - Any previously staged changes in the index will be lost. - - - Use indexpopulated only if the index file already contains exactly the - - contents of aref. + - When only one branch is specified, it is merged into the index. + - In this case, previously staged changes in the index are preserved. + - + - Should be run with a temporary index file configured by Git.useIndex. -} -merge :: Git.Repo -> String -> String -> String -> Bool -> IO () -merge g aref bref newref indexpopulated = do - stage g aref bref indexpopulated - commit g "union merge" newref [aref, bref] +merge :: Git.Repo -> [String] -> IO () +merge g (x:y:[]) = do + a <- ls_tree g x + b <- merge_trees g x y + update_index g (a++b) +merge g [x] = merge_tree_index g x >>= update_index g +merge _ _ = error "wrong number of branches to merge" -{- Stages the content of both refs into the index. -} -stage :: Git.Repo -> String -> String -> Bool -> IO () -stage g aref bref indexpopulated = do - -- Get the contents of aref, as a starting point, unless - -- the index is already populated with it. - ls <- if indexpopulated - then return [] - else fromgit ["ls-tree", "-z", "-r", "--full-tree", aref] - -- Identify files that are different between aref and bref, and - -- inject merged versions into git. - diff <- fromgit - ["diff-tree", "--raw", "-z", "-r", "--no-renames", "-l0", aref, bref] - ls' <- mapM mergefile (pairs diff) - -- Populate the index file. Later lines override earlier ones. - togit ["update-index", "-z", "--index-info"] - (join "\0" $ ls++catMaybes ls') +{- Feeds a list into update-index. Later items in the list can override + - earlier ones, so the list can be generated from any combination of + - ls_tree, merge_trees, and merge_tree. -} +update_index :: Git.Repo -> [String] -> IO () +update_index g l = togit ["update-index", "-z", "--index-info"] (join "\0" l) where - fromgit l = Git.pipeNullSplit g (map Param l) - togit l content = Git.pipeWrite g (map Param l) content + togit ps content = Git.pipeWrite g (map Param ps) content >>= forceSuccess +{- Gets the contents of a tree in a format suitable for update_index. -} +ls_tree :: Git.Repo -> String -> IO [String] +ls_tree g x = Git.pipeNullSplit g $ + map Param ["ls-tree", "-z", "-r", "--full-tree", x] + +{- For merging two trees. -} +merge_trees :: Git.Repo -> String -> String -> IO [String] +merge_trees g x y = calc_merge g + ["diff-tree", "--raw", "-z", "-r", "--no-renames", "-l0", x, y] + +{- For merging a single tree into the index. -} +merge_tree_index :: Git.Repo -> String -> IO [String] +merge_tree_index g x = calc_merge g + ["diff-index", "--raw", "-z", "-r", "--no-renames", "-l0", x] + +{- Calculates how to perform a merge, using git to get a raw diff, + - and returning a list suitable for update_index. -} +calc_merge :: Git.Repo -> [String] -> IO [String] +calc_merge g differ = do + diff <- Git.pipeNullSplit g $ map Param differ + l <- mapM mergefile (pairs diff) + return $ catMaybes l + where pairs [] = [] pairs (_:[]) = error "parse error" pairs (a:b:rest) = (a,b):pairs rest @@ -62,7 +77,7 @@ stage g aref bref indexpopulated = do mergefile (info, file) = do let [_colonamode, _bmode, asha, bsha, _status] = words info if bsha == nullsha - then return Nothing -- already staged from aref + then return Nothing -- already staged else mergefile' file asha bsha mergefile' file asha bsha = do let shas = filter (/= nullsha) [asha, bsha] @@ -70,10 +85,10 @@ stage g aref bref indexpopulated = do sha <- Git.hashObject g $ unionmerge content return $ Just $ ls_tree_line sha file -{- Commits the index into the specified branch. If refs are specified, - - commits a merge. -} +{- Commits the index into the specified branch, + - with the specified parent refs. -} commit :: Git.Repo -> String -> String -> [String] -> IO () -commit g message newref mergedrefs = do +commit g message newref parentrefs = do tree <- Git.getSha "write-tree" $ ignorehandle $ pipeFrom "git" ["write-tree"] sha <- Git.getSha "commit-tree" $ ignorehandle $ @@ -81,4 +96,4 @@ commit g message newref mergedrefs = do Git.run g "update-ref" [Param newref, Param sha] where ignorehandle a = return . snd =<< a - ps = concatMap (\r -> ["-p", r]) mergedrefs + ps = concatMap (\r -> ["-p", r]) parentrefs diff --git a/git-union-merge.hs b/git-union-merge.hs index f02db6be3d..7c0c1cd843 100644 --- a/git-union-merge.hs +++ b/git-union-merge.hs @@ -44,5 +44,6 @@ main = do g <- Git.configRead =<< Git.repoFromCwd Git.useIndex (tmpIndex g) setup g - GitUnionMerge.merge g aref bref newref False + GitUnionMerge.merge g [aref, bref] + GitUnionMerge.commit g "union merge" newref [aref, bref] cleanup g