From e816776a6247daa2adfa73d9029c6f155ae46b4a Mon Sep 17 00:00:00 2001
From: Joey Hess <joey@kitenet.net>
Date: Tue, 17 Jul 2012 15:57:49 -0400
Subject: [PATCH] add inodes to kqueue's directory cache

This is necessary to generate events when a file is deleted and immediately
replaced. Otherwise, the cache will have the old file, and so no event
would be generated.

Use of getFileStatus is suboptimal, it would be faster to use
the inode returned by readdir -- but getDirectoryContents does not expose
it, so I'd have to copy and modify a lot of low-level code.
---
 Utility/Kqueue.hs | 18 ++++++++++++------
 1 file changed, 12 insertions(+), 6 deletions(-)

diff --git a/Utility/Kqueue.hs b/Utility/Kqueue.hs
index 7e7e653ec3..17a5be5456 100644
--- a/Utility/Kqueue.hs
+++ b/Utility/Kqueue.hs
@@ -22,6 +22,7 @@ module Utility.Kqueue (
 import Common
 import Utility.Types.DirWatcher
 
+import System.Posix.Directory
 import System.Posix.Types
 import Foreign.C.Types
 import Foreign.C.Error
@@ -62,15 +63,19 @@ type DirMap = M.Map Fd DirInfo
 {- A directory, and its last known contents (with filenames relative to it) -}
 data DirInfo = DirInfo
 	{ dirName :: FilePath
-	, dirCache :: S.Set FilePath
+	, dirCache :: S.Set (FilePath, FileID)
 	}
 	deriving (Show)
 
 getDirInfo :: FilePath -> IO DirInfo
 getDirInfo dir = do
-	contents <- S.fromList . filter (not . dirCruft)
-		<$> getDirectoryContents dir
+	l <- filter (not . dirCruft) <$> getDirectoryContents dir
+	contents <- S.fromList <$> mapM addinode l
 	return $ DirInfo dir contents
+	where
+		addinode f = do
+			inode <- fileID <$> getFileStatus (dir </> f)
+			return (f, inode)
 
 {- Difference between the dirCaches of two DirInfos. -}
 (//) :: DirInfo -> DirInfo -> [Change]
@@ -78,7 +83,7 @@ oldc // newc = deleted ++ added
 	where
 		deleted = calc Deleted oldc newc
 		added   = calc Added newc oldc
-		calc a x y = map a . map (dirName x </>) $
+		calc a x y = map a . map (dirName x </>) . map fst $
 			S.toList $ S.difference (dirCache x) (dirCache y)
 
 {- Builds a map of directories in a tree, possibly pruning some.
@@ -99,7 +104,7 @@ scanRecursive topdir prune = M.fromList <$> walk [] [topdir]
 						case mfd of
 							Nothing -> walk c rest
 							Just fd -> do
-								let subdirs = map (dir </>) $
+								let subdirs = map (dir </>) . map fst $
 									S.toList $ dirCache info
 								walk ((fd, info):c) (subdirs ++ rest)
 
@@ -123,7 +128,8 @@ removeSubDir dirmap dir = do
 findDirContents :: DirMap -> FilePath -> [FilePath]
 findDirContents dirmap dir = concatMap absolutecontents $ search
 	where
-		absolutecontents i = map (dirName i </>) (S.toList $ dirCache i)
+		absolutecontents i = map (dirName i </>)
+			(map fst $ S.toList $ dirCache i)
 		search = map snd $ M.toList $
 			M.filter (\i -> dirName i == dir) dirmap