5e4deb3620
Git will eventually switch to sha2 and there will not be one single shaSize anymore, but two (40 and 64). Changed all parsers for git plumbing output to support both sizes of shas. One potential problem this does not deal with is, if somewhere in git-annex it reads two shas from different sources, and compares them to see if they're the same sha, it would fail if they're sha1 and sha256 of the same value. I don't know if that will really be a concern.
112 lines
3.8 KiB
Haskell
112 lines
3.8 KiB
Haskell
{- git-union-merge library
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-
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- Copyright 2011 Joey Hess <id@joeyh.name>
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-
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- Licensed under the GNU AGPL version 3 or higher.
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-}
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module Git.UnionMerge (
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merge,
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mergeIndex
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) where
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import qualified Data.ByteString.Lazy as L
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import qualified Data.ByteString.Lazy.Char8 as L8
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import qualified Data.Set as S
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import Common
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import Git
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import Git.Sha
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import Git.CatFile
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import Git.Command
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import Git.UpdateIndex
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import Git.HashObject
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import Git.Types
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import Git.FilePath
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{- Performs a union merge between two branches, staging it in the index.
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- Any previously staged changes in the index will be lost.
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-
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- Should be run with a temporary index file configured by useIndex.
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-}
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merge :: Ref -> Ref -> Repo -> IO ()
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merge x y repo = do
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hashhandle <- hashObjectStart True repo
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ch <- catFileStart repo
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streamUpdateIndex repo
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[ lsTree x repo
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, mergeTrees x y hashhandle ch repo
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]
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catFileStop ch
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hashObjectStop hashhandle
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{- Merges a list of branches into the index. Previously staged changes in
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- the index are preserved (and participate in the merge).
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-
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- update-index is run once per ref in turn, so that each ref is merged on
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- top of the merge for the previous ref. It would be more efficient, but
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- harder to calculate a single union merge involving all the refs, as well
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- as the index.
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-}
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mergeIndex :: HashObjectHandle -> CatFileHandle -> Repo -> [Ref] -> IO ()
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mergeIndex hashhandle ch repo bs = forM_ bs $ \b ->
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streamUpdateIndex repo [mergeTreeIndex b hashhandle ch repo]
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{- For merging two trees. -}
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mergeTrees :: Ref -> Ref -> HashObjectHandle -> CatFileHandle -> Repo -> Streamer
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mergeTrees (Ref x) (Ref y) hashhandle ch = doMerge hashhandle ch
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("diff-tree":diffOpts ++ [x, y, "--"])
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{- For merging a single tree into the index. -}
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mergeTreeIndex :: Ref -> HashObjectHandle -> CatFileHandle -> Repo -> Streamer
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mergeTreeIndex (Ref r) hashhandle ch = doMerge hashhandle ch $
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"diff-index" : diffOpts ++ ["--cached", r, "--"]
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diffOpts :: [String]
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diffOpts = ["--raw", "-z", "-r", "--no-renames", "-l0"]
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{- Streams update-index changes to perform a merge,
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- using git to get a raw diff. -}
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doMerge :: HashObjectHandle -> CatFileHandle -> [String] -> Repo -> Streamer
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doMerge hashhandle ch differ repo streamer = do
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(diff, cleanup) <- pipeNullSplit (map Param differ) repo
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go diff
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void $ cleanup
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where
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go [] = noop
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go (info:file:rest) = mergeFile (decodeBL' info) (L.toStrict file) hashhandle ch >>=
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maybe (go rest) (\l -> streamer l >> go rest)
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go (_:[]) = error $ "parse error " ++ show differ
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{- Given an info line from a git raw diff, and the filename, generates
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- a line suitable for update-index that union merges the two sides of the
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- diff. -}
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mergeFile :: String -> RawFilePath -> HashObjectHandle -> CatFileHandle -> IO (Maybe L.ByteString)
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mergeFile info file hashhandle h = case filter (`notElem` nullShas) [Ref asha, Ref bsha] of
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[] -> return Nothing
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(sha:[]) -> use sha
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shas -> use
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=<< either return (hashBlob hashhandle . L8.unlines)
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=<< calcMerge . zip shas <$> mapM getcontents shas
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where
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[_colonmode, _bmode, asha, bsha, _status] = words info
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use sha = return $ Just $
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updateIndexLine sha TreeFile $ asTopFilePath file
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-- Get file and split into lines to union merge.
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-- The encoding of the file is assumed to be either ASCII or utf-8;
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-- in either case it's safe to split on \n
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getcontents s = L8.lines <$> catObject h s
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{- Calculates a union merge between a list of refs, with contents.
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-
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- When possible, reuses the content of an existing ref, rather than
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- generating new content.
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-}
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calcMerge :: [(Ref, [L8.ByteString])] -> Either Ref [L8.ByteString]
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calcMerge shacontents
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| null reuseable = Right new
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| otherwise = Left $ fst $ Prelude.head reuseable
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where
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reuseable = filter (\c -> sorteduniq (snd c) == new) shacontents
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new = sorteduniq $ concat $ map snd shacontents
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sorteduniq = S.toList . S.fromList
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