From 5b345db370fc09cab1bfac29304432c37c3cb75c Mon Sep 17 00:00:00 2001
From: Simon Rettberg
Date: Thu, 1 Feb 2024 11:25:05 +0100
Subject: [slx-addons] Optimize addon activation (~1000% gain)

---
 modules.d/slx-addons/hooks/s3-setup-addons.sh | 21 +++++++++++++++------
 1 file changed, 15 insertions(+), 6 deletions(-)

diff --git a/modules.d/slx-addons/hooks/s3-setup-addons.sh b/modules.d/slx-addons/hooks/s3-setup-addons.sh
index 495e3799..5068d2c2 100755
--- a/modules.d/slx-addons/hooks/s3-setup-addons.sh
+++ b/modules.d/slx-addons/hooks/s3-setup-addons.sh
@@ -57,15 +57,24 @@ setup_addon() {
 	# purge addon-* files
 	rm -f -- addon-*
 
+	# make directory struct, replicate owners/perms - should we keep-old-files?
+	echo "Replicating directory tree in $NEWROOT"
+	# Doing this once in advance instead of doing a mkdir for each file's parent directory
+	# every time in the loop below brought us from 3.6s down to 2.2s for VMware
+	find . -type d -print0 | tar --no-recursion --null -T - -c | tar -C "$NEWROOT" --keep-old-files -x
 	# move all the files over
-	find . -not -type d 2>/dev/null | while read -r entry || [ -n "$entry" ]; do
-		entry="${entry#./}"
-		[ "$entry" != "${entry%/*}" ] && mkdir -p "${NEWROOT}/${entry%/*}"
-		mv -f -- "$entry" "${NEWROOT}/${entry}"
-	done
+	echo "Moving files over"
+	while read -r entry || [ -n "$entry" ]; do
+		# Doing the mv in parallel brought us from 2.2s to 380ms for VMware (~850 files),
+		# but I've no idea if there'd be an adverse effect if we had a lot more files
+		# to move and we'd spawn thousands of mv processes in parallel...
+		mv -f -- "$entry" "${NEWROOT}/${entry}" &
+	done < <( find . -not -type d ) # do it this way so we don't end up with a pipe-subshell
+	wait # and can properly wait for all the mv processes.
 
 	# post merge: remove files marked as whiteouts
 	# (e.g. they were removed during the addon installation)
+	echo "Applying whiteouts"
 	for WHITEOUT in "$NEWROOT/opt/openslx/etc/"*.whiteout; do
 		[ -e "$WHITEOUT" ] || continue
 		while read -r line; do
@@ -73,7 +82,7 @@ setup_addon() {
 		done < "$WHITEOUT"
 	done
 
-	cd - &>/dev/null
+	return 0
 }
 
 active=()
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