lifted out the kqueue and inotify to a generic DirWatcher interface

Kqueue code for dispatching events is not tested and probably doesn't
build.

Assistant/Watcher.hs

@@ -13,7 +13,8 @@ import Common.Annex
 import Assistant.ThreadedMonad
 import Assistant.DaemonStatus
 import Assistant.Committer
-import Utility.ThreadScheduler
+import Utility.DirWatcher
+import Utility.Types.DirWatcher
 import qualified Annex.Queue
 import qualified Git.Command
 import qualified Git.UpdateIndex
@@ -29,25 +30,12 @@ import Control.Concurrent.STM
 import Data.Bits.Utils
 import qualified Data.ByteString.Lazy as L
 
-#ifdef WITH_INOTIFY
-import Utility.Inotify
-import System.INotify
-#endif
-#ifdef WITH_KQUEUE
-import qualified Utility.Kqueue as Kqueue
-#endif
-
 checkCanWatch :: Annex ()
-checkCanWatch = do
-#if (WITH_INOTIFY || WITH_KQUEUE)
-	unlessM (liftIO (inPath "lsof") <||> Annex.getState Annex.force) $
-		needLsof
-#else
-#if defined linux_HOST_OS
-#warning "Building without inotify support; watch mode will be disabled."
-#endif
-	error "watch mode is not available on this system"
-#endif
+checkCanWatch
+	| canWatch = 
+		unlessM (liftIO (inPath "lsof") <||> Annex.getState Annex.force) $
+			needLsof
+	| otherwise = error "watch mode is not available on this system"
 
 needLsof :: Annex ()
 needLsof = error $ unlines
@@ -58,13 +46,9 @@ needLsof = error $ unlines
 	]
 
 watchThread :: ThreadState -> DaemonStatusHandle -> ChangeChan -> IO ()
-#ifdef WITH_INOTIFY
-watchThread st dstatus changechan = withINotify $ \i -> do
-	statupScan st dstatus $
-		watchDir i "." ignored hooks
-	-- Let the inotify thread run.
-	waitForTermination
+watchThread st dstatus changechan = watchDir "." ignored hooks startup
 	where
+		startup = statupScan st dstatus
 		hook a = Just $ runHandler st dstatus changechan a
 		hooks = WatchHooks
 			{ addHook = hook onAdd
@@ -73,21 +57,6 @@ watchThread st dstatus changechan = withINotify $ \i -> do
 			, delDirHook = hook onDelDir
 			, errHook = hook onErr
 			}
-#else
-#ifdef WITH_KQUEUE
-watchThread st dstatus changechan = do
-	kq <- statupScan st dstatus $
-		Kqueue.initKqueue "." ignored
-	go kq
-	where
-		go kq = do
-			(kq', changes) <- Kqueue.waitChange kq
-			print $ "detected a change in " ++ show changes
-			go kq'
-#else
-watchThread = undefined
-#endif /* WITH_KQUEUE */
-#endif /* WITH_INOTIFY */
 
 {- Initial scartup scan. The action should return once the scan is complete. -}
 statupScan :: ThreadState -> DaemonStatusHandle -> IO a -> IO a

Utility/DirWatcher.hs

@@ -0,0 +1,53 @@
+{- generic directory watching interface
+ -
+ - Uses either inotify or kqueue to watch a directory (and subdirectories)
+ - for changes, and runs hooks for different sorts of events as they occur.
+ -
+ - Copyright 2012 Joey Hess <joey@kitenet.net>
+ -
+ - Licensed under the GNU GPL version 3 or higher.
+ -}
+
+{-# LANGUAGE CPP #-}
+
+module Utility.DirWatcher where
+
+import Utility.Types.DirWatcher
+
+#if WITH_INOTIFY
+import qualified Utility.INotify as INotify
+import qualified System.INotify as INotify
+import Utility.ThreadScheduler
+#endif
+#if WITH_KQUEUE
+import qualified Utility.Kqueue as Kqueue
+#endif
+
+type Pruner = FilePath -> Bool
+
+canWatch :: Bool
+#if (WITH_INOTIFY || WITH_KQUEUE)
+canWatch = True
+#else
+#if defined linux_HOST_OS
+#warning "Building without inotify support"
+#endif
+canWatch = False
+#endif
+
+#if WITH_INOTIFY
+watchDir :: FilePath -> Pruner -> WatchHooks -> (IO () -> IO ()) -> IO ()
+watchDir dir prune hooks runstartup = INotify.withINotify $ \i -> do
+	runstartup $ INotify.watchDir i dir prune hooks
+	waitForTermination -- Let the inotify thread run.
+#else
+#if WITH_KQUEUE
+watchDir :: FilePath -> Pruner -> WatchHooks -> (IO Kqueue.Kqueue -> IO Kqueue.Kqueue) -> IO ()
+watchDir dir ignored hooks runstartup = do
+	kq <- runstartup $ Kqueue.initKqueue dir ignored
+	Kqueue.runHooks kq hooks
+#else
+watchDir :: FilePath -> Pruner -> WatchHooks -> (IO () -> IO ()) -> IO ()
+watchDir = undefined
+#endif
+#endif

Utility/INotify.hs

@@ -5,26 +5,17 @@
  - Licensed under the GNU GPL version 3 or higher.
  -}
 
-module Utility.Inotify where
+module Utility.INotify where
 
 import Common hiding (isDirectory)
 import Utility.ThreadLock
+import Utility.Types.DirWatcher
 
 import System.INotify
 import qualified System.Posix.Files as Files
 import System.IO.Error
 import Control.Exception (throw)
 
-type Hook a = Maybe (a -> Maybe FileStatus -> IO ())
-
-data WatchHooks = WatchHooks
-	{ addHook :: Hook FilePath
-	, addSymlinkHook :: Hook FilePath
-	, delHook :: Hook FilePath
-	, delDirHook :: Hook FilePath
-	, errHook :: Hook String -- error message
-	}
-
 {- Watches for changes to files in a directory, and all its subdirectories
  - that are not ignored, using inotify. This function returns after
  - its initial scan is complete, leaving a thread running. Callbacks are

Utility/Kqueue.hs

@@ -15,9 +15,11 @@ module Utility.Kqueue (
 	changedFile,
 	isAdd,
 	isDelete,
+	runHooks,
 ) where
 
 import Common
+import Utility.Types.DirWatcher
 
 import System.Posix.Types
 import Foreign.C.Types
@@ -187,3 +189,26 @@ handleChange (Kqueue h dirmap pruner) fd olddirinfo =
 			-- remove it from our map.
 			newmap <- removeSubDir dirmap (dirName olddirinfo)
 			return (Kqueue h newmap pruner, [])
+
+{- Processes changes on the Kqueue, calling the hooks as appropriate.
+ - Never returns. -}
+runHooks :: Kqueue -> WatchHooks -> IO ()
+runHooks kq hooks = do
+	(kq', changes) <- Kqueue.waitChange kq
+	forM_ changes $ dispatch kq'
+	runHooks kq' hooks
+	where
+		-- Kqueue returns changes for both whole directories
+		-- being added and deleted, and individual files being
+		-- added and deleted.
+		dispatch q change status
+			| isAdd change = withstatus s (dispatchadd q)
+			| isDelete change = callhook delDirHook change
+		dispatchadd q change s
+			| Files.isSymbolicLink = callhook addSymlinkHook change
+			| Files.isDirectory = print $ "TODO: recursive directory add: " ++ show change
+			| Files.isRegularFile = callhook addHook change
+			| otherwise = noop
+		callhook h change = hooks h $ changedFile change
+		withstatus change a = maybe noop (a change) =<<
+			(catchMaybeIO (getSymbolicLinkStatus (changedFile change)

Utility/Types/DirWatcher.hs

@@ -0,0 +1,22 @@
+{- generic directory watching types
+ -
+ - Copyright 2012 Joey Hess <joey@kitenet.net>
+ -
+ - Licensed under the GNU GPL version 3 or higher.
+ -}
+
+{-# LANGUAGE CPP #-}
+
+module Utility.Types.DirWatcher where
+
+import Common
+
+type Hook a = Maybe (a -> Maybe FileStatus -> IO ())
+
+data WatchHooks = WatchHooks
+	{ addHook :: Hook FilePath
+	, addSymlinkHook :: Hook FilePath
+	, delHook :: Hook FilePath
+	, delDirHook :: Hook FilePath
+	, errHook :: Hook String -- error message
+	}

debian/changelog

@@ -1,8 +1,9 @@
 git-annex (3.20120616) UNRELEASED; urgency=low
 
-  * watch: New subcommand, which uses inotify to watch for changes to
-    files and automatically annexes new files, etc, so you don't need
-    to manually run git commands when manipulating files.
+  * watch: New subcommand, a daemon which notices changes to
+    files and automatically annexes new files, etc, so you don't
+    need to manually run git commands when manipulating files.
+    Available on Linux, BSDs, and OSX!
   * Enable diskfree on kfreebsd, using statvfs.
 
  -- Joey Hess <joeyh@debian.org>  Tue, 12 Jun 2012 11:35:59 -0400