Fix a memory leak introduced in the last release

The problem was this line:

	cleanup = and <$> sequence (map snd v)

That caused all of v to be held onto until the end, when the cleanup action
was run.

I could not seem to find a bang pattern that avoided the leak, so I
resorted to a IORef, rather clunky, but not a performance problem because
it will only be written once per git ls-files, so typically just 1 time.

This commit was sponsored by Mark Reidenbach on Patreon.

CHANGELOG

@@ -1,6 +1,7 @@
 git-annex (8.20201008) UNRELEASED; urgency=medium
 
   * Fix build on Windows with network-3.
+  * Fix a memory leak introduced in the last release.
 
  -- Joey Hess <id@joeyh.name>  Thu, 08 Oct 2020 10:48:17 -0400
 

CmdLine/Seek.hs

@@ -48,6 +48,7 @@ import CmdLine.Action
 
 import Control.Concurrent.Async
 import System.Posix.Types
+import Data.IORef
 
 data AnnexedFileSeeker = AnnexedFileSeeker
 	{ startAction :: SeekInput -> RawFilePath -> Key -> CommandStart
@@ -416,18 +417,24 @@ seekFilteredKeys seeker listfs = do
 seekHelper :: (a -> RawFilePath) -> WarnUnmatchWhen -> ([LsFiles.Options] -> [RawFilePath] -> Git.Repo -> IO ([a], IO Bool)) -> WorkTreeItems -> Annex ([(SeekInput, a)], IO Bool)
 seekHelper c ww a (WorkTreeItems l) = do
 	os <- seekOptions ww
-	inRepo $ \g -> combinelists <$> forM (segmentXargsOrdered l)
-		(runSegmentPaths' mk c (\fs -> a os fs g) . map toRawFilePath)
+	v <- liftIO $ newIORef []
+	r <- inRepo $ \g -> concat . concat <$> forM (segmentXargsOrdered l)
+		(runSegmentPaths' mk c (\fs -> go v os fs g) . map toRawFilePath)
+	return (r, cleanupall v)
   where
 	mk (Just i) f = (SeekInput [fromRawFilePath i], f) 
 	-- This is not accurate, but it only happens when there are a
 	-- great many input WorkTreeItems.
 	mk Nothing f = (SeekInput [fromRawFilePath (c f)], f)
 
-	combinelists v = 
-		let r = concat $ concat $ map fst v
-		    cleanup = and <$> sequence (map snd v)
-		in (r, cleanup)
+	go v os fs g = do
+		(l, cleanup) <- a os fs g
+		liftIO $ modifyIORef' v (cleanup:)
+		return l
+
+	cleanupall v = do
+		cleanups <- readIORef v
+		and <$> sequence cleanups
 seekHelper _ _ _ NoWorkTreeItems = return ([], pure True)
 
 data WarnUnmatchWhen = WarnUnmatchLsFiles | WarnUnmatchWorkTreeItems

Utility/Path.hs

@@ -235,15 +235,11 @@ segmentPaths' f c (i:is) new =
  - than it would be to run the action separately with each path. In
  - the case of git file list commands, that assumption tends to hold.
  -}
-runSegmentPaths :: (a -> RawFilePath) -> ([RawFilePath] -> IO ([a], v)) -> [RawFilePath] -> IO ([[a]], v)
-runSegmentPaths c a paths = do
-	(l, cleanup) <- a paths
-	return (segmentPaths c paths l, cleanup)
+runSegmentPaths :: (a -> RawFilePath) -> ([RawFilePath] -> IO [a]) -> [RawFilePath] -> IO [[a]]
+runSegmentPaths c a paths = segmentPaths c paths <$> a paths
 
-runSegmentPaths' :: (Maybe RawFilePath -> a -> r) -> (a -> RawFilePath) -> ([RawFilePath] -> IO ([a], v)) -> [RawFilePath] -> IO ([[r]], v)
-runSegmentPaths' si c a paths = do
-	(l, cleanup) <- a paths
-	return (segmentPaths' si c paths l, cleanup)
+runSegmentPaths' :: (Maybe RawFilePath -> a -> r) -> (a -> RawFilePath) -> ([RawFilePath] -> IO [a]) -> [RawFilePath] -> IO [[r]]
+runSegmentPaths' si c a paths = segmentPaths' si c paths <$> a paths
 
 {- Converts paths in the home directory to use ~/ -}
 relHome :: FilePath -> IO String

doc/todo/memory_use_increase/comment_8_244acef6b20ac8fc281372f0898a49be._comment

@@ -0,0 +1,12 @@
+[[!comment format=mdwn
+ username="joey"
+ subject="""comment 8"""
+ date="2020-10-13T19:52:50Z"
+ content="""
+[[!commit f624876dc21fed141eee368c86f4b209852ab91c]] is where seekHelper
+went bad. Fixed that.
+
+git-annex is still allocating 120 mb in this situation, though the
+profile now shows a max memory use of 4 mb. Still don't understand that, so
+this remains open.
+"""]]