wip RawFilePath

Goal is to make git-annex faster by using ByteString for all the
worktree traversal. For now, this is focusing on Command.Find,
in order to benchmark how much it helps. (All other commands are
temporarily disabled)

Currently in a very bad unbuildable in-between state.

Git/Branch.hs

@@ -16,6 +16,8 @@ import Git.Command
 import qualified Git.Config
 import qualified Git.Ref
 
+import qualified Data.ByteString as B
+
 {- The currently checked out branch.
  -
  - In a just initialized git repo before the first commit,
@@ -29,19 +31,19 @@ current r = do
 	case v of
 		Nothing -> return Nothing
 		Just branch -> 
-			ifM (null <$> pipeReadStrict [Param "show-ref", Param $ fromRef branch] r)
+			ifM (B.null <$> pipeReadStrict [Param "show-ref", Param $ fromRef branch] r)
 				( return Nothing
 				, return v
 				)
 
 {- The current branch, which may not really exist yet. -}
 currentUnsafe :: Repo -> IO (Maybe Branch)
-currentUnsafe r = parse . firstLine
+currentUnsafe r = parse . firstLine'
 	<$> pipeReadStrict [Param "symbolic-ref", Param "-q", Param $ fromRef Git.Ref.headRef] r
   where
-	parse l
-		| null l = Nothing
-		| otherwise = Just $ Git.Ref l
+	parse b
+		| B.null b = Nothing
+		| otherwise = Just $ Git.Ref $ decodeBS b
 
 {- Checks if the second branch has any commits not present on the first
  - branch. -}
@@ -53,7 +55,8 @@ changed origbranch newbranch repo
   where
 
 changed' :: Branch -> Branch -> [CommandParam] -> Repo -> IO String
-changed' origbranch newbranch extraps repo = pipeReadStrict ps repo
+changed' origbranch newbranch extraps repo =
+	decodeBS <$> pipeReadStrict ps repo
   where
 	ps =
 		[ Param "log"
@@ -72,7 +75,7 @@ changedCommits origbranch newbranch extraps repo =
  -
  - This requires there to be a path from the old to the new. -}
 fastForwardable :: Ref -> Ref -> Repo -> IO Bool
-fastForwardable old new repo = not . null <$>
+fastForwardable old new repo = not . B.null <$>
 	pipeReadStrict
 		[ Param "log"
 		, Param $ fromRef old ++ ".." ++ fromRef new
@@ -160,7 +163,7 @@ commitCommand' runner commitmode ps = runner $
 commit :: CommitMode -> Bool -> String -> Branch -> [Ref] -> Repo -> IO (Maybe Sha)
 commit commitmode allowempty message branch parentrefs repo = do
 	tree <- getSha "write-tree" $
-		pipeReadStrict [Param "write-tree"] repo
+		decodeBS' <$> pipeReadStrict [Param "write-tree"] repo
 	ifM (cancommit tree)
 		( do
 			sha <- commitTree commitmode message parentrefs tree repo