Fix zombie leak and general inneficiency when copying files to a local git repo.

Benchmarking this with 1000 small files being copied, the time reduced from
15.98s to 14.64s -- an 8% improvement in the non-data-transfer overhead of
git-annex copy.

Annex.hs

@@ -88,6 +88,7 @@ data AnnexState = AnnexState
 	, gitconfig :: GitConfig
 	, backends :: [BackendA Annex]
 	, remotes :: [Types.Remote.RemoteA Annex]
+	, remoteannexstate :: M.Map UUID AnnexState
 	, output :: MessageState
 	, force :: Bool
 	, fast :: Bool
@@ -128,6 +129,7 @@ newState c r = AnnexState
 	, gitconfig = c
 	, backends = []
 	, remotes = []
+	, remoteannexstate = M.empty
 	, output = defaultMessageState
 	, force = False
 	, fast = False

Remote/Git.hs

@@ -144,7 +144,7 @@ repoAvail r
 				else return True
 	| Git.repoIsUrl r = return True
 	| Git.repoIsLocalUnknown r = return False
-	| otherwise = liftIO $ catchBoolIO $ onLocal r $ return True
+	| otherwise = liftIO $ isJust <$> catchMaybeIO (Git.Config.read r)
 
 {- Tries to read the config for a specified remote, updates state, and
  - returns the updated repo. -}
@@ -161,9 +161,12 @@ tryGitConfigRead r
 	| Git.repoIsHttp r = store geturlconfig
 	| Git.GCrypt.isEncrypted r = handlegcrypt =<< getConfigMaybe (remoteConfig r "uuid")
 	| Git.repoIsUrl r = return r
-	| otherwise = store $ safely $ onLocal r $ do 
-		ensureInitialized
-		Annex.getState Annex.repo
+	| otherwise = store $ safely $ do
+		s <- Annex.new r
+		Annex.eval s $ do
+			Annex.BranchState.disableUpdate
+			ensureInitialized
+			Annex.getState Annex.repo
   where
 	haveconfig = not . M.null . Git.config
 
@@ -267,8 +270,8 @@ inAnnex rmt key
 	checkremote = Ssh.inAnnex r key
 	checklocal = guardUsable r (cantCheck r) $ dispatch <$> check
 	  where
-		check = liftIO $ catchMsgIO $ onLocal r $
-			Annex.Content.inAnnexSafe key
+		check = either (Left . show) Right 
+			<$> tryAnnex (onLocal rmt $ Annex.Content.inAnnexSafe key)
 		dispatch (Left e) = Left e
 		dispatch (Right (Just b)) = Right b
 		dispatch (Right Nothing) = cantCheck r
@@ -291,7 +294,7 @@ keyUrls r key = map tourl locs'
 dropKey :: Remote -> Key -> Annex Bool
 dropKey r key
 	| not $ Git.repoIsUrl (repo r) =
-		guardUsable (repo r) False $ commitOnCleanup r $ liftIO $ onLocal (repo r) $ do
+		guardUsable (repo r) False $ commitOnCleanup r $ onLocal r $ do
 			ensureInitialized
 			whenM (Annex.Content.inAnnex key) $ do
 				Annex.Content.lockContent key $
@@ -311,7 +314,7 @@ copyFromRemote' r key file dest
 		let params = Ssh.rsyncParams r Download
 		u <- getUUID
 		-- run copy from perspective of remote
-		liftIO $ onLocal (repo r) $ do
+		onLocal r $ do
 			ensureInitialized
 			v <- Annex.Content.prepSendAnnex key
 			case v of
@@ -410,7 +413,7 @@ copyToRemote r key file p
 		let params = Ssh.rsyncParams r Upload
 		u <- getUUID
 		-- run copy from perspective of remote
-		liftIO $ onLocal (repo r) $ ifM (Annex.Content.inAnnex key)
+		onLocal r $ ifM (Annex.Content.inAnnex key)
 			( return True
 			, do
 				ensureInitialized
@@ -439,19 +442,40 @@ fsckOnRemote r params
 
 {- The passed repair action is run in the Annex monad of the remote. -}
 repairRemote :: Git.Repo -> Annex Bool -> Annex (IO Bool)
-repairRemote r a = return $ Remote.Git.onLocal r a
-
-{- Runs an action on a local repository inexpensively, by making an annex
- - monad using that repository. -}
-onLocal :: Git.Repo -> Annex a -> IO a
-onLocal r a = do
+repairRemote r a = return $ do
 	s <- Annex.new r
 	Annex.eval s $ do
-		-- No need to update the branch; its data is not used
-		-- for anything onLocal is used to do.
 		Annex.BranchState.disableUpdate
+		ensureInitialized
 		a
 
+{- Runs an action from the perspective of a local remote.
+ -
+ - The AnnexState is cached for speed and to avoid resource leaks.
+ -
+ - The repository's git-annex branch is not updated, as an optimisation.
+ - No caller of onLocal can query data from the branch and be ensured
+ - it gets a current value. Caller of onLocal can make changes to
+ - the branch, however.
+ -}
+onLocal :: Remote -> Annex a -> Annex a
+onLocal r a = do
+	m <- Annex.getState Annex.remoteannexstate
+	case M.lookup (uuid r) m of
+		Nothing -> do
+			st <- liftIO $ Annex.new (repo r)
+			go st $ do
+				Annex.BranchState.disableUpdate	
+				a
+		Just st -> go st a
+  where
+	cache st = Annex.changeState $ \s -> s
+		{ Annex.remoteannexstate = M.insert (uuid r) st (Annex.remoteannexstate s) }
+	go st a' = do
+		(ret, st') <- liftIO $ Annex.run st a'
+		cache st'
+		return ret
+
 {- Copys a file with rsync unless both locations are on the same
  - filesystem. Then cp could be faster. -}
 rsyncOrCopyFile :: [CommandParam] -> FilePath -> FilePath -> MeterUpdate -> Annex Bool
@@ -488,7 +512,7 @@ commitOnCleanup r a = go `after` a
   where
 	go = Annex.addCleanup (Git.repoLocation $ repo r) cleanup
 	cleanup
-		| not $ Git.repoIsUrl (repo r) = liftIO $ onLocal (repo r) $
+		| not $ Git.repoIsUrl (repo r) = onLocal r $
 			doQuietSideAction $
 				Annex.Branch.commit "update"
 		| otherwise = void $ do

debian/changelog

@@ -1,3 +1,10 @@
+git-annex (5.20140307) UNRELEASED; urgency=medium
+
+  * Fix zombie leak and general inneficiency when copying files to a
+    local git repo.
+
+ -- Joey Hess <joeyh@debian.org>  Thu, 06 Mar 2014 16:17:01 -0400
+
 git-annex (5.20140306) unstable; urgency=high
 
   * sync: Fix bug in direct mode that caused a file that was not