Clear elements cache instead of refreshing it (#17708)

Author: nikolajlauridsen

src/Umbraco.PublishedCache.HybridCache/NotificationHandlers/CacheRefreshingNotificationHandler.cs

@@ -45,7 +45,7 @@ public CacheRefreshingNotificationHandler(
 
     public async Task HandleAsync(ContentRefreshNotification notification, CancellationToken cancellationToken)
     {
-        await RefreshElementsCacheAsync(notification.Entity);
+        ClearElementsCache();
 
         await _documentCacheService.RefreshContentAsync(notification.Entity);
     }
@@ -54,73 +54,36 @@ public async Task HandleAsync(ContentDeletedNotification notification, Cancellat
     {
         foreach (IContent deletedEntity in notification.DeletedEntities)
         {
-            RemoveFromElementsCache(deletedEntity);
+            ClearElementsCache();
             await _documentCacheService.DeleteItemAsync(deletedEntity);
         }
     }
 
     public async Task HandleAsync(MediaRefreshNotification notification, CancellationToken cancellationToken)
     {
-        await RefreshElementsCacheAsync(notification.Entity);
+        ClearElementsCache();
         await _mediaCacheService.RefreshMediaAsync(notification.Entity);
     }
 
     public async Task HandleAsync(MediaDeletedNotification notification, CancellationToken cancellationToken)
     {
         foreach (IMedia deletedEntity in notification.DeletedEntities)
         {
-            RemoveFromElementsCache(deletedEntity);
+            ClearElementsCache();
             await _mediaCacheService.DeleteItemAsync(deletedEntity);
         }
     }
 
-    private async Task RefreshElementsCacheAsync(IUmbracoEntity content)
+    private void ClearElementsCache()
     {
-        IEnumerable<IRelation> parentRelations = _relationService.GetByParent(content)!;
-        IEnumerable<IRelation> childRelations = _relationService.GetByChild(content);
-
-        var ids = parentRelations.Select(x => x.ChildId).Concat(childRelations.Select(x => x.ParentId)).ToHashSet();
-        // We need to add ourselves to the list of ids to clear
-        ids.Add(content.Id);
-        foreach (var id in ids)
-        {
-            if (await _documentCacheService.HasContentByIdAsync(id) is false)
-            {
-                continue;
-            }
-
-            IPublishedContent? publishedContent = await _documentCacheService.GetByIdAsync(id);
-            if (publishedContent is null)
-            {
-                continue;
-            }
-
-            foreach (IPublishedProperty publishedProperty in publishedContent.Properties)
-            {
-                var property = (PublishedProperty) publishedProperty;
-                if (property.ReferenceCacheLevel is PropertyCacheLevel.Elements
-                    || property.PropertyType.DeliveryApiCacheLevel is PropertyCacheLevel.Elements
-                    || property.PropertyType.DeliveryApiCacheLevelForExpansion is PropertyCacheLevel.Elements)
-                {
-                    _elementsCache.ClearByKey(property.ValuesCacheKey);
-                }
-            }
-        }
+        // Ideally we'd like to not have to clear the entire cache here. However, this was the existing behavior in NuCache.
+        // The reason for this is that we have no way to know which elements are affected by the changes. or what their keys are.
+        // This is because currently published elements lives exclusively in a JSON blob in the umbracoPropertyData table.
+        // This means that the only way to resolve these keys are to actually parse this data with a specific value converter, and for all cultures, which is not feasible.
+        // If published elements become their own entities with relations, instead of just property data, we can revisit this,
+        _elementsCache.Clear();
     }
 
-    private void RemoveFromElementsCache(IUmbracoEntity content)
-    {
-        // ClearByKey clears by "startsWith" so we'll clear by the cachekey prefix + contentKey
-        // This will clear any and all properties for this content item, this is important because
-        // we cannot resolve the PublishedContent for this entity since it and its content type is deleted.
-        _elementsCache.ClearByKey(GetContentWideCacheKey(content.Key, true));
-        _elementsCache.ClearByKey(GetContentWideCacheKey(content.Key, false));
-    }
-
-    private string GetContentWideCacheKey(Guid contentKey, bool isPreviewing) => isPreviewing
-        ? CacheKeys.PreviewPropertyCacheKeyPrefix + contentKey
-        : CacheKeys.PropertyCacheKeyPrefix + contentKey;
-
     public Task HandleAsync(ContentTypeRefreshedNotification notification, CancellationToken cancellationToken)
     {
         const ContentTypeChangeTypes types // only for those that have been refreshed