message/classes/time_last_message_between_users.php

   1 <?php
   2 // This file is part of Moodle - http://moodle.org/
   3 //
   4 // Moodle is free software: you can redistribute it and/or modify
   5 // it under the terms of the GNU General Public License as published by
   6 // the Free Software Foundation, either version 3 of the License, or
   7 // (at your option) any later version.
   8 //
   9 // Moodle is distributed in the hope that it will be useful,
  10 // but WITHOUT ANY WARRANTY; without even the implied warranty of
  11 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12 // GNU General Public License for more details.
  13 //
  14 // You should have received a copy of the GNU General Public License
  15 // along with Moodle.  If not, see <http://www.gnu.org/licenses/>.
  16
  17 /**
  18  * Cache data source for the time of the last message between users.
  19  *
  20  * @package    core_message
  21  * @category   cache
  22  * @copyright  2016 Ryan Wyllie <ryan@moodle.com>
  23  * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
  24  */
  25
  26 namespace core_message;
  27
  28 defined('MOODLE_INTERNAL') || die();
  29
  30 /**
  31  * Cache data source for the time of the last message in a conversation.
  32  *
  33  * @package    core_message
  34  * @category   cache
  35  * @copyright  2016 Ryan Wyllie <ryan@moodle.com>
  36  * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
  37  */
  38 class time_last_message_between_users implements \cache_data_source {
  39
  40     /** @var time_last_message_between_users the singleton instance of this class. */
  41     protected static $instance = null;
  42
  43     /**
  44      * Returns an instance of the data source class that the cache can use for loading data using the other methods
  45      * specified by the cache_data_source interface.
  46      *
  47      * @param \cache_definition $definition
  48      * @return object
  49      */
  50     public static function get_instance_for_cache(\cache_definition $definition) {
  51         if (is_null(self::$instance)) {
  52             self::$instance = new time_last_message_between_users();
  53         }
  54         return self::$instance;
  55     }
  56
  57     /**
  58      * Loads the data for the key provided ready formatted for caching.
  59      *
  60      * @param string|int $key The key to load.
  61      * @return mixed What ever data should be returned, or false if it can't be loaded.
  62      */
  63     public function load_for_cache($key) {
  64         $message = api::get_most_recent_conversation_message($key);
  65
  66         if ($message) {
  67             return $message->timecreated;
  68         } else {
  69             return null;
  70         }
  71     }
  72
  73     /**
  74      * Loads several keys for the cache.
  75      *
  76      * @param array $keys An array of keys each of which will be string|int.
  77      * @return array An array of matching data items.
  78      */
  79     public function load_many_for_cache(array $keys) {
  80         $results = [];
  81
  82         foreach ($keys as $key) {
  83             $results[] = $this->load_for_cache($key);
  84         }
  85
  86         return $results;
  87     }
  88 }