Avoid looping if long-running git cat-file or git hash-object crashes and keeps crashing when restarted.

Git/Command.hs

@@ -128,9 +128,14 @@ leaveZombie = fst
 
 {- Runs a git command as a coprocess. -}
 gitCoProcessStart :: Bool -> [CommandParam] -> Repo -> IO CoProcess.CoProcessHandle
-gitCoProcessStart restartable params repo = CoProcess.start restartable "git"
+gitCoProcessStart restartable params repo = CoProcess.start numrestarts "git"
 	(toCommand $ gitCommandLine params repo)
 	(gitEnv repo)
+  where
+  	{- If a long-running git command like cat-file --batch
+	 - crashes, it will likely start up again ok. If it keeps crashing
+	 - 10 times, something is badly wrong. -}
+	numrestarts = if restartable then 10 else 0
 
 gitCreateProcess :: [CommandParam] -> Repo -> CreateProcess
 gitCreateProcess params repo =

Utility/CoProcess.hs

@@ -30,15 +30,15 @@ data CoProcessState = CoProcessState
 	}
 
 data CoProcessSpec = CoProcessSpec
-	{ coProcessRestartable :: Bool
+	{ coProcessNumRestarts :: Int
 	, coProcessCmd :: FilePath
 	, coProcessParams :: [String]
 	, coProcessEnv :: Maybe [(String, String)]
 	}
 
-start :: Bool -> FilePath -> [String] -> Maybe [(String, String)] -> IO CoProcessHandle
+start :: Int -> FilePath -> [String] -> Maybe [(String, String)] -> IO CoProcessHandle
-start restartable cmd params env = do
+start numrestarts cmd params env = do
-	s <- start' $ CoProcessSpec restartable cmd params env
+	s <- start' $ CoProcessSpec numrestarts cmd params env
 	newMVar s
 
 start' :: CoProcessSpec -> IO CoProcessState
@@ -66,7 +66,7 @@ query ch send receive = do
 				return
   where
   	restartable s a cont
-		| coProcessRestartable (coProcessSpec s) =
+		| coProcessNumRestarts (coProcessSpec s) > 0 =
 			maybe restart cont =<< catchMaybeIO a
 		| otherwise = cont =<< a
 	restart = do
@@ -75,7 +75,8 @@ query ch send receive = do
 			hClose $ coProcessTo s
 			hClose $ coProcessFrom s
 		void $ waitForProcess $ coProcessPid s
-		s' <- start' (coProcessSpec s)
+		s' <- start' $ (coProcessSpec s)
+			{ coProcessNumRestarts = coProcessNumRestarts (coProcessSpec s) - 1 }
 		putMVar ch s'
 		query ch send receive
 

debian/changelog

@@ -6,6 +6,8 @@ git-annex (5.20131231) UNRELEASED; urgency=medium
     in subdirectories to go missing.
   * Windows: Avoid eating stdin when running ssh to add a authorized key,
     since this is used for password prompting.
+  * Avoid looping if long-running git cat-file or git hash-object crashes
+    and keeps crashing when restarted.
 
  -- Joey Hess <joeyh@debian.org>  Tue, 31 Dec 2013 13:41:18 -0400
 

doc/bugs/endless_loop_when_PWD_gone.mdwn

@@ -12,3 +12,5 @@ This results in git-annex entering an endless loop:
     fatal: Unable to read current working directory: No such file or directory
     fatal: Unable to read current working directory: No such file or directory
     fatal: Unable to read current working directory: No such file or directory
+
+> [[fixed|done]] --[[Joey]]