public function countUnreadMessagesForConversationList($conversationIdList, $userId)
 {
     if (count($conversationIdList) == 0) {
         return array();
     }
     $list = $this->messageDao->countUnreadMessagesForConversationList($conversationIdList, $userId);
     $result = array();
     foreach ($list as $item) {
         $result[$item['conversationId']] = $item['count'];
     }
     return $result;
 }