1 files changed, 60 insertions, 9 deletions

diff --git a/indra/newview/llinventoryobserver.cpp b/indra/newview/llinventoryobserver.cpp
index e4a7b17966..86147d65e6 100644
--- a/indra/newview/llinventoryobserver.cpp
+++ b/indra/newview/llinventoryobserver.cpp
@@ -669,36 +669,87 @@ void LLInventoryCategoriesObserver::changed(U32 mask)
 		if (!category)
 			continue;
 
-		S32 version = category->getVersion();
-		if (version != (*iter).second.mVersion)
+		const S32 version = category->getVersion();
+		const S32 expected_num_descendents = category->getDescendentCount();
+		if ((version == LLViewerInventoryCategory::VERSION_UNKNOWN) ||
+			(expected_num_descendents == LLViewerInventoryCategory::DESCENDENT_COUNT_UNKNOWN))
 		{
-			// Update category version in map.
-			(*iter).second.mVersion = version;
-			(*iter).second.mCallback();
+			continue;
+		}
+
+		// Check number of known descendents to find out whether it has changed.
+		LLInventoryModel::cat_array_t* cats;
+		LLInventoryModel::item_array_t* items;
+		gInventory.getDirectDescendentsOf((*iter).first, cats, items);
+		if (!cats || !items)
+		{
+			llwarns << "Category '" << category->getName() << "' descendents corrupted, fetch failed." << llendl;
+			// NULL means the call failed -- cats/items map doesn't exist (note: this does NOT mean
+			// that the cat just doesn't have any items or subfolders).
+			// Unrecoverable, so just skip this category.
+
+			llassert(cats != NULL && items != NULL);
+		}
+		const S32 current_num_known_descendents = cats->count() + items->count();
+
+		LLCategoryData cat_data = (*iter).second;
+
+		// If category version or descendents count has changed
+		// update category data in mCategoryMap and fire a callback.
+		if (version != cat_data.mVersion || current_num_known_descendents != cat_data.mDescendentsCount)
+		{
+			cat_data.mVersion = version;
+			cat_data.mDescendentsCount = current_num_known_descendents;
+
+			cat_data.mCallback();
 		}
 	}
 }
 
-void LLInventoryCategoriesObserver::addCategory(const LLUUID& cat_id, callback_t cb)
+bool LLInventoryCategoriesObserver::addCategory(const LLUUID& cat_id, callback_t cb)
 {
 	S32 version;
+	S32 current_num_known_descendents;
+	bool can_be_added = true;
+
 	LLViewerInventoryCategory* category = gInventory.getCategory(cat_id);
 	if (category)
 	{
 		// Inventory category version is used to find out if some changes
 		// to a category have been made.
 		version = category->getVersion();
+
+		LLInventoryModel::cat_array_t* cats;
+		LLInventoryModel::item_array_t* items;
+		gInventory.getDirectDescendentsOf(cat_id, cats, items);
+		if (!cats || !items)
+		{
+			llwarns << "Category '" << category->getName() << "' descendents corrupted, fetch failed." << llendl;
+			// NULL means the call failed -- cats/items map doesn't exist (note: this does NOT mean
+			// that the cat just doesn't have any items or subfolders).
+			// Unrecoverable, so just return "false" meaning that the category can't be observed.
+			can_be_added = false;
+
+			llassert(cats != NULL && items != NULL);
+		}
+		current_num_known_descendents = cats->count() + items->count();
 	}
 	else
 	{
 		// If category could not be retrieved it might mean that
 		// inventory is unusable at the moment so the category is
-		// stored with VERSION_UNKNOWN and it may be updated later.
+		// stored with VERSION_UNKNOWN and DESCENDENT_COUNT_UNKNOWN,
+		// it may be updated later.
 		version = LLViewerInventoryCategory::VERSION_UNKNOWN;
+		current_num_known_descendents = LLViewerInventoryCategory::DESCENDENT_COUNT_UNKNOWN;
+	}
+
+	if (can_be_added)
+	{
+		mCategoryMap.insert(category_map_value_t(cat_id, LLCategoryData(cb, version, current_num_known_descendents)));
 	}
 
-	version = category->getVersion();
-	mCategoryMap.insert(category_map_value_t(cat_id, LLCategoryData(cb, version)));
+	return can_be_added;
 }
 
 void LLInventoryCategoriesObserver::removeCategory(const LLUUID& cat_id)