From f4a3fac4da12c63fc3d48c5aea3a4a2efe72d39f Mon Sep 17 00:00:00 2001
From: Ned Anderson <NedAnd1@users.noreply.github.com>
Date: Thu, 31 Aug 2023 21:42:39 -0400
Subject: [PATCH] chore: genericize event refresher list

---
 pkg/controller/common.go       | 57 ++++++++++++++++------------------
 pkg/controller/shared_state.go | 22 ++++++++-----
 2 files changed, 42 insertions(+), 37 deletions(-)

diff --git a/pkg/controller/common.go b/pkg/controller/common.go
index d0bd08630f..481ed1911f 100644
--- a/pkg/controller/common.go
+++ b/pkg/controller/common.go
@@ -1189,51 +1189,48 @@ func WatchObject(mgr manager.Manager, objKind source.Kind) error {
 	return err
 }
 
-// circular linked list with simple accessibility to the current event, etc.
-type eventRefresherList struct {
-	curr *eventRefresherNode
+type circularLinkedList[T any] struct {
+	*circularLinkedListNode[T]
 }
 
-type eventRefresherNode struct {
-	prev      *eventRefresherNode
-	next      *eventRefresherNode
-	message   string
-	timestamp time.Time
-	objects   []runtime.Object
+type circularLinkedListNode[T any] struct {
+	curr T
+	prev *circularLinkedListNode[T]
+	next *circularLinkedListNode[T]
 }
 
-func (events eventRefresherList) isEmpty() bool {
-	return events.curr == nil
+func (list circularLinkedList[T]) isEmpty() bool {
+	return list.circularLinkedListNode == nil
 }
 
-func (events *eventRefresherList) clear() {
-	events.curr = nil
+func (list *circularLinkedList[T]) clear() {
+	list.circularLinkedListNode = nil
 }
 
-func (events *eventRefresherList) add(newEvent *eventRefresherNode) {
-	if events.curr == nil {
-		events.curr = newEvent
+func (list *circularLinkedList[T]) add(newNode *circularLinkedListNode[T]) {
+	if list.circularLinkedListNode == nil {
+		list.circularLinkedListNode = newNode
 	} else {
-		events.curr.prev.next = newEvent
+		list.prev.next = newNode
 	}
-	newEvent.next = events.curr
-	events.curr.prev = newEvent
+	newNode.next = list.circularLinkedListNode
+	list.prev = newNode
 }
 
-// Moves to the next event in the list and retrieves it.
-func (events *eventRefresherList) next() *eventRefresherNode {
-	nextEvent := events.curr.next
-	events.curr = nextEvent
-	return nextEvent
+// Moves to the next node in the list and retrieves it.
+func (list *circularLinkedList[T]) next() *circularLinkedListNode[T] {
+	nextNode := list.circularLinkedListNode.next
+	list.circularLinkedListNode = nextNode
+	return nextNode
 }
 
-func (oldEvent *eventRefresherNode) remove() {
-	oldEvent.prev.next = oldEvent.next
-	oldEvent.next.prev = oldEvent.prev
+func (oldNode *circularLinkedListNode[T]) remove() {
+	oldNode.prev.next = oldNode.next
+	oldNode.next.prev = oldNode.prev
 }
 
-func (oldEvent *eventRefresherNode) tryRemove() {
-	if oldEvent != nil {
-		oldEvent.remove()
+func (oldNode *circularLinkedListNode[T]) tryRemove() {
+	if oldNode != nil {
+		oldNode.remove()
 	}
 }
diff --git a/pkg/controller/shared_state.go b/pkg/controller/shared_state.go
index fbfbcde9e4..6bcb547a12 100644
--- a/pkg/controller/shared_state.go
+++ b/pkg/controller/shared_state.go
@@ -1400,10 +1400,16 @@ func (c *SharedState) createEventQueues() {
 }
 
 func (c *SharedState) _eventRefresherRoutine() {
+	type eventInfo struct {
+		message   string
+		timestamp time.Time
+		objects   []runtime.Object
+	}
+
 	var eventTTL = time.Duration(c.config.ControllerConfig.EventTTLInSec) * time.Second
-	eventMap := map[string]*eventRefresherNode{}
+	eventMap := map[string]*circularLinkedListNode[eventInfo]{}
 
-	var events eventRefresherList
+	var events circularLinkedList[eventInfo]
 	var lastTime time.Time
 	var delay time.Duration            // how long the alarm was last set to wait for
 	expLatency := eventOverlapVariance // we request the alarm to wake us up earlier by this amount, to negate latency due to other operations and timer imprecision
@@ -1416,15 +1422,17 @@ func (c *SharedState) _eventRefresherRoutine() {
 		select {
 		case newFailureInfo := <-c.eventsToPersistQueue:
 			// add the new failure
-			newEvent := &eventRefresherNode{
-				message:   newFailureInfo.message,
-				objects:   newFailureInfo.pods,
-				timestamp: newFailureInfo.timestamp.Add(eventTTL - eventOverlapDuration),
+			newEvent := &circularLinkedListNode[eventInfo]{
+				curr: eventInfo{
+					message:   newFailureInfo.message,
+					objects:   newFailureInfo.pods,
+					timestamp: newFailureInfo.timestamp.Add(eventTTL - eventOverlapDuration),
+				},
 			}
 
 			if events.isEmpty() {
 				lastTime = time.Now()
-				delay = newEvent.timestamp.Sub(lastTime) - expLatency
+				delay = newEvent.curr.timestamp.Sub(lastTime) - expLatency
 				alarm.Reset(delay)
 			}