From 530a5092a65a413fead598484878274504b08154 Mon Sep 17 00:00:00 2001
From: "W. Trevor King" <wking@tremily.us>
Date: Mon, 6 Mar 2023 05:21:30 -0800
Subject: [PATCH] pkg/cvo/availableupdates: Prioritize conditional risks for
 largest target version

When changing channels it's possible that multiple new conditional
update risks will need to be evaluated.  For instance, a cluster
running 4.10.34 in a 4.10 channel might only have to evaluate
OpenStackNodeCreationFails.  But when the channel is changed to a 4.11
channel multiple new risks require evaluation and the evaluation of
new risks was throttled at one every 10 minutes.  This means if there
are three new risks it may take up to 20 minutes after the channel has
changed for the full set of conditional updates to be computed.

With this commit, I'm sorting the conditional updates in
version-descending order, which is the order we've used in the
ClusterVersion status since c9dd4792f3ef (pkg/cvo/availableupdates:
Sort (conditional)updates, 2021-09-29, #663).  This prioritizes the
longest-hop risks.  For example, 4.10.34 currently has the following
updates:

* 4.10.(z!=38): no risks
* 4.10.38: OpenStackNodeCreationFails
* 4.11.(z<10): ARM64SecCompError524, AWSOldBootImagesLackAfterburn, MachineConfigRenderingChurn, OVNNetworkPolicyLongName
* 4.11.(10<=z<26): ARM64SecCompError524, AWSOldBootImagesLackAfterburn, MachineConfigRenderingChurn
* 4.11.26: ARM64SecCompError524, AWSOldBootImagesLackAfterburn
* 4.11.(27<=z<...): AWSOldBootImagesLackAfterburn

By focusing on the largest target (say 4.11.30), we'd evaluate
AWSOldBootImagesLackAfterburn first.  If it did not match the current
cluster, 4.11.27 and later would be quickly recommended.  It would
take another 10m before the self-throttling allowed us to evaluate
ARM64SecCompError524, and once we had, that would unblock 4.11.26.
Ten minutes after that, we'd evaluate MachineConfigRenderingChurn, and
unblock 4.11.(10<=z<26).  And so on.  But folks on 4.10.34 today are
much more likely to be interested in 4.11.30 and other tip releases
than they are to care about 4.11.10 and other relatively old releases.
---
 pkg/cvo/availableupdates.go | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/pkg/cvo/availableupdates.go b/pkg/cvo/availableupdates.go
index 7aec2faa17..bd50d3f8b8 100644
--- a/pkg/cvo/availableupdates.go
+++ b/pkg/cvo/availableupdates.go
@@ -301,6 +301,12 @@ func (u *availableUpdates) evaluateConditionalUpdates(ctx context.Context) {
 		return
 	}
 
+	sort.Slice(u.ConditionalUpdates, func(i, j int) bool {
+		vi := semver.MustParse(u.ConditionalUpdates[i].Release.Version)
+		vj := semver.MustParse(u.ConditionalUpdates[j].Release.Version)
+		return vi.GTE(vj)
+	})
+
 	for i, conditionalUpdate := range u.ConditionalUpdates {
 		if errorCondition := evaluateConditionalUpdate(ctx, &conditionalUpdate); errorCondition != nil {
 			meta.SetStatusCondition(&conditionalUpdate.Conditions, *errorCondition)