Fixes: #U4-2041, #U4-2040 - user cache is not invalidated when permissions change across LB environments, also streamlined how caching is handled in

these classes which now use the standardized events way to do things. Fixes a performance issue and ensures that the cache is not invalidated for 'micro'
operations during permission changes.

src/Umbraco.Web/Cache/CacheRefresherEventHandler.cs

@@ -77,6 +77,12 @@ namespace Umbraco.Web.Cache
             User.Saving += UserSaving;
             User.Deleting += UserDeleting;
 
+            //Bind to permission events
+
+            Permission.New += PermissionNew;
+            Permission.Updated += PermissionUpdated;
+            Permission.Deleted += PermissionDeleted;
+
             //Bind to template events
             //NOTE: we need to bind to legacy and new API events currently: http://issues.umbraco.org/issue/U4-1979
 
@@ -105,7 +111,7 @@ namespace Umbraco.Web.Cache
             MediaService.Moving += MediaServiceMoving;
             MediaService.Trashing += MediaServiceTrashing;
         }
-
+        
         #region Dictionary event handlers
 
         static void LocalizationServiceSavedDictionaryItem(ILocalizationService sender, Core.Events.SaveEventArgs<IDictionaryItem> e)
@@ -301,6 +307,22 @@ namespace Umbraco.Web.Cache
         #endregion
         
         #region User event handlers
+
+        static void PermissionDeleted(UserPermission sender, DeleteEventArgs e)
+        {
+            InvalidateCacheForPermissionsChange(sender);
+        }
+
+        static void PermissionUpdated(UserPermission sender, SaveEventArgs e)
+        {
+            InvalidateCacheForPermissionsChange(sender);
+        }
+
+        static void PermissionNew(UserPermission sender, NewEventArgs e)
+        {
+            InvalidateCacheForPermissionsChange(sender);
+        }
+        
         static void UserDeleting(User sender, System.EventArgs e)
         {
             DistributedCache.Instance.RemoveUserCache(sender.Id);
@@ -309,7 +331,24 @@ namespace Umbraco.Web.Cache
         static void UserSaving(User sender, System.EventArgs e)
         {
             DistributedCache.Instance.RefreshUserCache(sender.Id);
-        } 
+        }
+
+        private static void InvalidateCacheForPermissionsChange(UserPermission sender)
+        {
+            if (sender.User != null)
+            {
+                DistributedCache.Instance.RefreshUserCache(sender.User.Id);
+            }
+            if (sender.UserId > -1)
+            {
+                DistributedCache.Instance.RefreshUserCache(sender.UserId);
+            }
+            if (sender.Nodes.Any())
+            {
+                DistributedCache.Instance.RefreshAllUserCache();
+            }
+        }
+
         #endregion
 
         #region Template event handlers

src/Umbraco.Web/Cache/DistributedCacheExtensions.cs

@@ -22,6 +22,11 @@ namespace Umbraco.Web.Cache
         public static void RefreshUserCache(this DistributedCache dc, int userId)
         {
             dc.Refresh(new Guid(DistributedCache.UserCacheRefresherId), userId);
+        }
+
+        public static void RefreshAllUserCache(this DistributedCache dc)
+        {
+            dc.RefreshAll(new Guid(DistributedCache.UserCacheRefresherId));
         } 
         #endregion