fix(TTL): don't add items into expiration map on update if item has n…

…o expiration

If an item was already in the cache, adding it again will cause it to be
added into the expiration map, even if the item has no expiration set.

This effectively is a memory leak. There is no clean up of this "zero
time" bucket, and it will keep growing.

ttl.go

@@ -89,6 +89,11 @@ func (m *expirationMap[_]) update(key, conflict uint64, oldExpTime, newExpTime t
 		delete(oldBucket, key)
 	}
 
+	// Items that don't expire don't need to be in the expiration map.
+	if newExpTime.IsZero() {
+		return
+	}
+
 	newBucketNum := storageBucket(newExpTime)
 	newBucket, ok := m.buckets[newBucketNum]
 	if !ok {
@@ -160,7 +165,7 @@ func (m *expirationMap[V]) cleanup(store store[V], policy policy[V], onEvict fun
 
 // clear clears the expirationMap, the caller is responsible for properly
 // evicting the referenced items
-func (m *expirationMap) clear() {
+func (m *expirationMap[V]) clear() {
 	if m == nil {
 		return
 	}