convert all git read/write functions to use ByteStrings

This yields a second or so speedup in unused, find, etc. Seems that even
when the ByteString is immediately split and then converted to Strings,
it's faster.

I may try to push ByteStrings out into more of git-annex gradually,
although I suspect most of the time-critical parts are already covered
now, and many of the rest rely on libraries that only support Strings.

1 files changed, 3 insertions, 2 deletions

diff --git a/Branch.hs b/Branch.hs
index 92b1fe29e..e4caeece7 100644
--- a/Branch.hs
+++ b/Branch.hs
@@ -30,6 +30,7 @@ import System.IO
 import System.IO.Binary
 import System.Posix.Process
 import System.Exit
+import qualified Data.ByteString.Lazy.Char8 as L
 
 import Types.BranchState
 import qualified Git
@@ -181,7 +182,7 @@ siblingBranches :: Annex [String]
 siblingBranches = do
 	g <- Annex.gitRepo
 	r <- liftIO $ Git.pipeRead g [Param "show-ref", Param name]
-	return $ map (last . words) (lines r)
+	return $ map (last . words . L.unpack) (L.lines r)
 
 {- Ensures that a given ref has been merged into the index. -}
 updateRef :: GitRef -> Annex (Maybe String)
@@ -196,7 +197,7 @@ updateRef ref
 			Param (name++".."++ref),
 			Params "--oneline -n1"
 			]
-		if null diffs
+		if L.null diffs
 			then return Nothing
 			else do
 				showSideAction $ "merging " ++ Git.refDescribe ref ++ " into " ++ name