annex.startupscan can be set to false to disable the assistant's startup scan.

Assistant/Threads/Merger.hs

@@ -39,7 +39,7 @@ mergeThread = namedThread "Merger" $ do
 		, modifyHook = changehook
 		, errHook = errhook
 		}
-	void $ liftIO $ watchDir dir (const False) hooks id
+	void $ liftIO $ watchDir dir (const False) True hooks id
 	debug ["watching", dir]
 
 type Handler = FilePath -> Assistant ()

Assistant/Threads/TransferWatcher.hs

@@ -35,7 +35,7 @@ transferWatcherThread = namedThread "TransferWatcher" $ do
 		, modifyHook = modifyhook
 		, errHook = errhook
 		}
-	void $ liftIO $ watchDir dir (const False) hooks id
+	void $ liftIO $ watchDir dir (const False) True hooks id
 	debug ["watching for transfers"]
 
 type Handler = FilePath -> Assistant ()

Assistant/Threads/UpgradeWatcher.hs

@@ -50,8 +50,9 @@ upgradeWatcherThread urlrenderer = namedThread "UpgradeWatcher" $ do
 		let dir = parentDir flagfile
 		let depth = length (splitPath dir) + 1
 		let nosubdirs f = length (splitPath f) == depth
-		void $ liftIO $ watchDir dir nosubdirs hooks (startup mvar)
+		void $ liftIO $ watchDir dir nosubdirs False hooks (startup mvar)
   	-- Ignore bogus events generated during the startup scan.
+	-- We ask the watcher to not generate them, but just to be safe..
   	startup mvar scanner = do
 		r <- scanner
 		void $ swapMVar mvar Started

Assistant/Threads/Watcher.hs

@@ -102,7 +102,8 @@ runWatcher = do
 		, delDirHook = deldirhook
 		, errHook = errhook
 		}
-	handle <- liftIO $ watchDir "." ignored hooks startup
+	scanevents <- liftAnnex $ annexStartupScan <$> Annex.getGitConfig
+	handle <- liftIO $ watchDir "." ignored scanevents hooks startup
 	debug [ "watching", "."]
 	
 	{- Let the DirWatcher thread run until signalled to pause it,

Types/GitConfig.hs

@@ -51,6 +51,7 @@ data GitConfig = GitConfig
 	, annexSecureEraseCommand :: Maybe String
 	, annexGenMetaData :: Bool
 	, annexListen :: Maybe String
+	, annexStartupScan :: Bool
 	, coreSymlinks :: Bool
 	, gcryptId :: Maybe String
 	}
@@ -85,6 +86,7 @@ extractGitConfig r = GitConfig
 	, annexSecureEraseCommand = getmaybe (annex "secure-erase-command")
 	, annexGenMetaData = getbool (annex "genmetadata") False
 	, annexListen = getmaybe (annex "listen")
+	, annexStartupScan = getbool (annex "startupscan") True
 	, coreSymlinks = getbool "core.symlinks" True
 	, gcryptId = getmaybe "core.gcrypt-id"
 	}

Utility/DirWatcher.hs

@@ -104,33 +104,33 @@ modifyTracked = undefined
  - to shutdown later. -}
 #if WITH_INOTIFY
 type DirWatcherHandle = INotify.INotify
-watchDir :: FilePath -> Pruner -> WatchHooks -> (IO () -> IO ()) -> IO DirWatcherHandle
-watchDir dir prune hooks runstartup = do
+watchDir :: FilePath -> Pruner -> Bool -> WatchHooks -> (IO () -> IO ()) -> IO DirWatcherHandle
+watchDir dir prune scanevents hooks runstartup = do
 	i <- INotify.initINotify
-	runstartup $ INotify.watchDir i dir prune hooks
+	runstartup $ INotify.watchDir i dir prune scanevents hooks
 	return i
 #else
 #if WITH_KQUEUE
 type DirWatcherHandle = ThreadId
-watchDir :: FilePath -> Pruner -> WatchHooks -> (IO Kqueue.Kqueue -> IO Kqueue.Kqueue) -> IO DirWatcherHandle
-watchDir dir prune hooks runstartup = do
+watchDir :: FilePath -> Pruner -> Bool -> WatchHooks -> (IO Kqueue.Kqueue -> IO Kqueue.Kqueue) -> IO DirWatcherHandle
+watchDir dir prune _scanevents hooks runstartup = do
 	kq <- runstartup $ Kqueue.initKqueue dir prune
 	forkIO $ Kqueue.runHooks kq hooks
 #else
 #if WITH_FSEVENTS
 type DirWatcherHandle = FSEvents.EventStream
-watchDir :: FilePath -> Pruner -> WatchHooks -> (IO FSEvents.EventStream -> IO FSEvents.EventStream) -> IO DirWatcherHandle
-watchDir dir prune hooks runstartup =
-	runstartup $ FSEvents.watchDir dir prune hooks
+watchDir :: FilePath -> Pruner -> Bool -> WatchHooks -> (IO FSEvents.EventStream -> IO FSEvents.EventStream) -> IO DirWatcherHandle
+watchDir dir prune scanevents hooks runstartup =
+	runstartup $ FSEvents.watchDir dir prune scanevents hooks
 #else
 #if WITH_WIN32NOTIFY
 type DirWatcherHandle = Win32Notify.WatchManager
-watchDir :: FilePath -> Pruner -> WatchHooks -> (IO Win32Notify.WatchManager -> IO Win32Notify.WatchManager) -> IO DirWatcherHandle
-watchDir dir prune hooks runstartup =
-	runstartup $ Win32Notify.watchDir dir prune hooks
+watchDir :: FilePath -> Pruner -> Bool -> WatchHooks -> (IO Win32Notify.WatchManager -> IO Win32Notify.WatchManager) -> IO DirWatcherHandle
+watchDir dir prune scanevents hooks runstartup =
+	runstartup $ Win32Notify.watchDir dir prune scanevents hooks
 #else
 type DirWatcherHandle = ()
-watchDir :: FilePath -> Pruner -> WatchHooks -> (IO () -> IO ()) -> IO DirWatcherHandle
+watchDir :: FilePath -> Pruner -> Bool -> WatchHooks -> (IO () -> IO ()) -> IO DirWatcherHandle
 watchDir = undefined
 #endif
 #endif

Utility/DirWatcher/FSEvents.hs

@@ -14,8 +14,8 @@ import System.OSX.FSEvents
 import qualified System.Posix.Files as Files
 import Data.Bits ((.&.))
 
-watchDir :: FilePath -> (FilePath -> Bool) -> WatchHooks -> IO EventStream
-watchDir dir ignored hooks = do
+watchDir :: FilePath -> (FilePath -> Bool) -> Bool -> WatchHooks -> IO EventStream
+watchDir dir ignored scanevents hooks = do
 	unlessM fileLevelEventsSupported $
 		error "Need at least OSX 10.7.0 for file-level FSEvents"
 	scan dir
@@ -79,9 +79,11 @@ watchDir dir ignored hooks = do
 					Nothing -> noop
 					Just s
 						| Files.isSymbolicLink s ->
-							runhook addSymlinkHook ms
+							when scanevents $
+								runhook addSymlinkHook ms
 						| Files.isRegularFile s ->
-							runhook addHook ms
+							when scanevents $
+								runhook addHook ms
 						| otherwise ->
 							noop
 		  where

Utility/DirWatcher/INotify.hs

@@ -46,8 +46,8 @@ import Control.Exception (throw)
  - So this will fail if there are too many subdirectories. The
  - errHook is called when this happens.
  -}
-watchDir :: INotify -> FilePath -> (FilePath -> Bool) -> WatchHooks -> IO ()
-watchDir i dir ignored hooks
+watchDir :: INotify -> FilePath -> (FilePath -> Bool) -> Bool -> WatchHooks -> IO ()
+watchDir i dir ignored scanevents hooks
 	| ignored dir = noop
 	| otherwise = do
 		-- Use a lock to make sure events generated during initial
@@ -61,7 +61,7 @@ watchDir i dir ignored hooks
 				mapM_ scan =<< filter (not . dirCruft) <$>
 					getDirectoryContents dir
   where
-	recurse d = watchDir i d ignored hooks
+	recurse d = watchDir i d ignored scanevents hooks
 
 	-- Select only inotify events required by the enabled
 	-- hooks, but always include Create so new directories can
@@ -85,9 +85,11 @@ watchDir i dir ignored hooks
 				| Files.isDirectory s ->
 					recurse $ indir f
 				| Files.isSymbolicLink s ->
-					runhook addSymlinkHook f ms
+					when scanevents $
+						runhook addSymlinkHook f ms
 				| Files.isRegularFile s ->
-					runhook addHook f ms
+					when scanevents $
+						runhook addHook f ms
 				| otherwise ->
 					noop
 

Utility/DirWatcher/Win32Notify.hs

@@ -13,8 +13,8 @@ import Utility.DirWatcher.Types
 import System.Win32.Notify
 import qualified Utility.PosixFiles as Files
 
-watchDir :: FilePath -> (FilePath -> Bool) -> WatchHooks -> IO WatchManager
-watchDir dir ignored hooks = do
+watchDir :: FilePath -> (FilePath -> Bool) -> Bool -> WatchHooks -> IO WatchManager
+watchDir dir ignored scanevents hooks = do
 	scan dir
 	wm <- initWatchManager
 	void $ watchDirectory wm dir True [Create, Delete, Modify, Move] handle
@@ -52,7 +52,8 @@ watchDir dir ignored hooks = do
 					Nothing -> noop
 					Just s
 						| Files.isRegularFile s ->
-							runhook addHook ms
+							when scanevents $
+								runhook addHook ms
 						| otherwise ->
 							noop
 		  where

debian/changelog

@@ -7,6 +7,8 @@ git-annex (5.20140228) UNRELEASED; urgency=medium
   * webapp: No longer supports a port specified after --listen, since
     it was buggy, and that use case is better supported by setting up HTTPS.
   * annex.listen can be configured, instead of using --listen
+  * annex.startupscan can be set to false to disable the assistant's startup
+    scan.
   * Probe for quvi version at run time.
   * webapp: Filter out from Switch Repository list any
     repositories listed in autostart file that don't have a

doc/git-annex.mdwn

@@ -1380,6 +1380,13 @@ Here are all the supported configuration settings.
   Set to false to prevent the git-annex assistant from automatically
   committing changes to files in the repository.
 
+* `annex.startupscan`
+
+  Set to false to prevent the git-annex assistant from scanning the
+  repository for new and changed files on startup. This will prevent it
+  from noticing changes that were made while it was not running, but can be
+  a useful performance tweak for a large repository.
+
 * `annex.listen`
 
   Configures which address the webapp listens on. The default is localhost.