[pacman-dev] [PATCH 2/2] pkgdelta: implement requirments for delta generation

[Florian Pritz]

Big deltas or deltas for very small packages are not needed so we should
check that and not generate any.

Signed-off-by: Florian Pritz <bluewind at xinu.at>
---
 scripts/pkgdelta.sh.in |   33 ++++++++++++++++++++++++++++++---
 1 file changed, 30 insertions(+), 3 deletions(-)

diff --git a/scripts/pkgdelta.sh.in b/scripts/pkgdelta.sh.in
index 806ae23..ff34d88 100644
--- a/scripts/pkgdelta.sh.in
+++ b/scripts/pkgdelta.sh.in
@@ -30,6 +30,13 @@ declare -r myver='@PACKAGE_VERSION@'
 
 QUIET=0
 
+# minimal of package before deltas are generated (bytes)
+min_pkg_size=$((1024*1024))
+
+# percent of new package above which the delta will be discarded
+max_delta_size=80
+
+
 # ensure we have a sane umask set
 umask 0022
 
@@ -46,6 +53,8 @@ This delta file can then be added to a database using repo-add.\n\n")"
 	echo
 	printf -- "$(gettext "Options:\n")"
 	printf -- "  -q                ""$(gettext "quiet\n")"
+	printf -- "  --min-pkg-size    ""$(gettext "minimal of package before deltas are generated (bytes)\n")"
+	printf -- "  --max-delta-size  ""$(gettext "percent of new package above which the delta will be discarded\n")"
 }
 
 version() {
@@ -96,6 +105,13 @@ create_xdelta()
 	newver="$pkgver"
 	newarch="$arch"
 
+	pkgsize="$(@SIZECMD@ -L "$newfile")"
+
+	if ((pkgsize < min_pkg_size)); then
+		msg "$(gettext "Ignoring small package: %s")" "$pkgsize"
+		return 0
+	fi
+
 	if [[ $oldname != "$newname" ]]; then
 		error "$(gettext "The package names don't match : '%s' and '%s'")" "$oldname" "$newname"
 		return 1
@@ -119,10 +135,19 @@ create_xdelta()
 	if (( ret )); then
 		error "$(gettext "Delta could not be created.")"
 		return 1
-	else
-		msg "$(gettext "Generated delta : '%s'")" "$deltafile"
-		(( QUIET )) && echo "$deltafile"
 	fi
+
+	deltasize="$(@SIZECMD@ -L "$deltafile")"
+
+	if ((max_delta_size * pkgsize / 100 < deltasize)); then
+		msg "$(gettext "Ignoring big delta: %s vs %s")" "$deltasize" "$pkgsize"
+		rm -f "$deltafile"
+		return 0
+	fi
+
+	msg "$(gettext "Generated delta : '%s'")" "$deltafile"
+	(( QUIET )) && echo "$deltafile"
+
 	return 0
 }
 
@@ -134,6 +159,8 @@ while (( $# )); do
 		-h|--help)    usage; exit 0 ;;
 		-V|--version) version; exit 0 ;;
 		-q|--quiet) QUIET=1;;
+		--min-pkg-size) min_pkg_size=$2; shift;;
+		--max-delta-size) max_delta_size=$2; shift;;
 		*) args+=("$1");;
 	esac
 	shift
-- 
1.7.9.6