From 9014df94724c7b30484933f1df6aea79fbda716a Mon Sep 17 00:00:00 2001
From: Steve Baker <sbaker@redhat.com>
Date: Thu, 7 Feb 2019 16:25:37 +1300
Subject: [PATCH] Speed up execution time of yum_update.sh

Doing a yum update with an explicit list of packages where many of
those packages are already up-to-date has a significant time penalty.
This change includes version comparison to remove packages from
packages_for_update where the installed and available versions are
identical.

This change also only installs yum-plugin-priorities if it is not
already installed, for some extra time saving.

For a specific example of time saved, I had a
centos-binary-rsyslog-base with the following timings.

Without this change
-------------------
packages passed to yum update: 87
packages actually updated:     11
time taken                     35s

With this change
-------------------
packages passed to yum update: 11
packages actually updated:     11
time taken                     10s

This time saved should add up over all of the container images during
image prepare in CI.

Change-Id: Ie282acd1cdc0de8d875959ec9578122fe34f98ac
---
 files/yum_update.sh | 22 +++++++++++++++++-----
 1 file changed, 17 insertions(+), 5 deletions(-)

diff --git a/files/yum_update.sh b/files/yum_update.sh
index 62c15fd..ed9546c 100755
--- a/files/yum_update.sh
+++ b/files/yum_update.sh
@@ -4,9 +4,17 @@ set -eoux pipefail
 
 packages_for_update=
 if [ -n "$1" ] && command -v repoquery >/dev/null 2>&1; then
-    installed=$(rpm -qa --qf "%{NAME}\n" | sort)
-    available=$(repoquery --provides --disablerepo='*' --enablerepo=$1 --qf %{NAME} -a | cut -d= -f1 | sort)
-    packages_for_update=$(comm -12 <(printf "%s\n" $installed) <(printf "%s\n" $available))
+    installed_versions=$(rpm -qa --qf "%{NAME} = %{VERSION}-%{RELEASE}\n" | sort)
+    available_versions=$(repoquery --provides --disablerepo='*' --enablerepo=$1 -a | sort)
+    uptodate_versions=$(comm -12 <(printf "%s\n" "$installed_versions") <(printf "%s\n" "$available_versions"))
+
+
+    installed=$(printf "%s\n" "$installed_versions" | cut -d= -f1 | sort)
+    available=$(printf "%s\n" "$available_versions" | cut -d= -f1 | sort)
+    uptodate=$(printf "%s\n" "$uptodate_versions" | cut -d= -f1 | sort)
+
+    installed_for_update=$(comm -23 <(printf "%s\n" $installed) <(printf "%s\n" $uptodate))
+    packages_for_update=$(comm -12 <(printf "%s\n" $installed_for_update) <(printf "%s\n" $available))
 fi
 
 if [ -z "$packages_for_update" ]; then
@@ -18,9 +26,13 @@ PKG="$(command -v dnf || command -v yum)"
 PKG_MGR="$(echo ${PKG:(-3)})"
 
 if [ $PKG_MGR == "dnf" ]; then
-    $PKG install -y dnf-plugins-core
+    if ! echo $installed | grep -qw dnf-plugins-core; then
+        $PKG install -y dnf-plugins-core
+    fi
 else:
-    $PKG install -y yum-plugin-priorities
+    if ! echo $installed | grep -qw yum-plugin-priorities; then
+        $PKG install -y yum-plugin-priorities
+    fi
 fi
 $PKG -y update $packages_for_update
 rm -rf /var/cache/$PKG_MGR