From c4f1465a814356173b541de5053dfe40b4a43297 Mon Sep 17 00:00:00 2001
From: Joey Hess <joeyh@joeyh.name>
Date: Mon, 14 Jun 2021 11:53:51 -0400
Subject: [PATCH] check symlink before reading file

This is faster because when multiple files are in a directory, it gets
cached.
---
 Annex/Link.hs                                       | 13 +++++--------
 ...ent_25_5525b58ec94084a926c71f749d1f4233._comment |  8 ++++++++
 2 files changed, 13 insertions(+), 8 deletions(-)
 create mode 100644 doc/bugs/significant_performance_regression_impacting_datal/comment_25_5525b58ec94084a926c71f749d1f4233._comment

diff --git a/Annex/Link.hs b/Annex/Link.hs
index 50f2717fcb..c305b39bd7 100644
--- a/Annex/Link.hs
+++ b/Annex/Link.hs
@@ -301,7 +301,7 @@ unpaddedMaxPointerSz = 8192
  - symlink does. Avoids a false positive in those cases.
  - -}
 isPointerFile :: RawFilePath -> IO (Maybe Key)
-isPointerFile f = catchDefaultIO Nothing $ do
+isPointerFile f = catchDefaultIO Nothing $
 #if defined(mingw32_HOST_OS)
 	checkcontentfollowssymlinks -- no symlinks supported on windows
 #else
@@ -311,13 +311,10 @@ isPointerFile f = catchDefaultIO Nothing $ do
 		closeFd
 		(\fd -> readhandle =<< fdToHandle fd)
 #else
-	pointercontent <- checkcontentfollowssymlinks
-	if isJust pointercontent
-		then ifM (isSymbolicLink <$> R.getSymbolicLinkStatus f)
-			( return Nothing
-			, return pointercontent
-			)
-		else return Nothing
+	ifM (isSymbolicLink <$> R.getSymbolicLinkStatus f)
+		( return Nothing
+		, checkcontentfollowssymlinks
+		)
 #endif
 #endif
   where
diff --git a/doc/bugs/significant_performance_regression_impacting_datal/comment_25_5525b58ec94084a926c71f749d1f4233._comment b/doc/bugs/significant_performance_regression_impacting_datal/comment_25_5525b58ec94084a926c71f749d1f4233._comment
new file mode 100644
index 0000000000..ca226f11a4
--- /dev/null
+++ b/doc/bugs/significant_performance_regression_impacting_datal/comment_25_5525b58ec94084a926c71f749d1f4233._comment
@@ -0,0 +1,8 @@
+[[!comment format=mdwn
+ username="joey"
+ subject="""comment 25"""
+ date="2021-06-14T15:52:37Z"
+ content="""
+Found an optimisation that sped it up 50%, but this edge case is still 
+`O(N^2)`, so *shrug*.
+"""]]