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authorGravatar Joey Hess <joey@kitenet.net>2011-12-12 01:33:02 -0400
committerGravatar Joey Hess <joey@kitenet.net>2011-12-12 01:59:29 -0400
commitacd7a52dfd2cad24fd946ffcf8c4b1d07eb474ce (patch)
tree7a93b0f04d270fcc479ec89ff68eed6430270dc2 /Git
parent0cbab5de657e025057dd10b087a874d6b3a7b13e (diff)
always find optimal merge
Testing b9ac5854549636493449fea6830364a01159fbf6, it didn't find the optimal union merge, the second sha was the one to use, at least in the case I tried. Let's just try all shas to see if any can be reused. I stopped using the expensive nub, so despite the use of sets to sort/uniq file contents, this is probably as fast or faster than it was before.
Diffstat (limited to 'Git')
-rw-r--r--Git/UnionMerge.hs34
1 files changed, 20 insertions, 14 deletions
diff --git a/Git/UnionMerge.hs b/Git/UnionMerge.hs
index 89fcf83e0..0345af399 100644
--- a/Git/UnionMerge.hs
+++ b/Git/UnionMerge.hs
@@ -15,8 +15,8 @@ module Git.UnionMerge (
) where
import System.Cmd.Utils
-import Data.List
import qualified Data.ByteString.Lazy.Char8 as L
+import qualified Data.Set as S
import Common
import Git
@@ -103,22 +103,14 @@ calc_merge ch differ repo streamer = gendiff >>= go
mergeFile :: String -> FilePath -> CatFileHandle -> Repo -> IO (Maybe String)
mergeFile info file h repo = case filter (/= nullsha) [Ref asha, Ref bsha] of
[] -> return Nothing
- (sha:[]) -> return $ Just $ update_index_line sha file
- (sha:shas) -> do
- newsha <- maybe (return sha) (hashObject repo . L.unlines) =<<
- unionmerge
- <$> (L.lines <$> catObject h sha)
- <*> (map L.lines <$> mapM (catObject h) shas)
- return $ Just $ update_index_line newsha file
+ (sha:[]) -> use sha
+ shas -> use =<< either return (hashObject repo . L.unlines) =<<
+ calcMerge . zip shas <$> mapM getcontents shas
where
[_colonmode, _bmode, asha, bsha, _status] = words info
nullsha = Ref $ replicate shaSize '0'
-
- unionmerge origcontent content
- | newcontent == origcontent = Nothing
- | otherwise = Just newcontent
- where
- newcontent = nub $ concat $ origcontent:content
+ getcontents s = L.lines <$> catObject h s
+ use sha = return $ Just $ update_index_line sha file
{- Injects some content into git, returning its Sha. -}
hashObject :: Repo -> L.ByteString -> IO Sha
@@ -131,3 +123,17 @@ hashObject repo content = getSha subcmd $ do
where
subcmd = "hash-object"
params = [subcmd, "-w", "--stdin"]
+
+{- Calculates a union merge between a list of refs, with contents.
+ -
+ - When possible, reuses the content of an existing ref, rather than
+ - generating new content.
+ -}
+calcMerge :: [(Ref, [L.ByteString])] -> Either Ref [L.ByteString]
+calcMerge shacontents
+ | null reuseable = Right $ new
+ | otherwise = Left $ fst $ head reuseable
+ where
+ reuseable = filter (\c -> sorteduniq (snd c) == new) shacontents
+ new = sorteduniq $ concat $ map snd shacontents
+ sorteduniq = S.toList . S.fromList