MDL-80300 mod_quiz: Add override manager class

mod/quiz/classes/cache/overrides.php

@@ -64,6 +64,11 @@ public static function get_instance_for_cache(cache_definition $definition): ove
     public function load_for_cache($key) {
         global $DB;
 
+        // Ignore getting data if this is a cache invalidation - {@see \cache_helper::purge_by_event()}.
+        if ($key == 'lastinvalidation') {
+            return null;
+        }
+
         [$quizid, $ug, $ugid] = explode('_', $key);
         $quizid = (int) $quizid;
 

mod/quiz/classes/local/override_cache.php

@@ -0,0 +1,127 @@
+<?php
+// This file is part of Moodle - http://moodle.org/
+//
+// Moodle is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// Moodle is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with Moodle.  If not, see <http://www.gnu.org/licenses/>.
+
+namespace mod_quiz\local;
+
+/**
+ * Cache manager for quiz overrides
+ *
+ * Override cache data is set via its data source, {@see \mod_quiz\cache\overrides}
+ * @package   mod_quiz
+ * @copyright 2024 Matthew Hilton <matthewhilton@catalyst-au.net>
+ * @license   http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+class override_cache {
+
+    /** @var string invalidation event used to purge data when reset_userdata is called, {@see \cache_helper::purge_by_event()}**/
+    public const INVALIDATION_USERDATARESET = 'userdatareset';
+
+    /**
+     * Create override_cache object and link to quiz
+     *
+     * @param int $quizid The quiz to link this cache to
+     */
+    public function __construct(
+        /** @var int $quizid ID of quiz cache is being operated on **/
+        protected readonly int $quizid
+    ) {
+    }
+
+    /**
+     * Returns the override cache
+     *
+     * @return cache
+     */
+    protected function get_cache(): \cache {
+        return \cache::make('mod_quiz', 'overrides');
+    }
+
+    /**
+     * Returns group cache key
+     *
+     * @param int $groupid
+     * @return string the group cache key
+     */
+    protected function get_group_cache_key(int $groupid): string {
+        return "{$this->quizid}_g_{$groupid}";
+    }
+
+    /**
+     * Returns user cache key
+     *
+     * @param int $userid
+     * @return string the user cache key
+     */
+    protected function get_user_cache_key(int $userid): string {
+        return "{$this->quizid}_u_{$userid}";
+    }
+
+    /**
+     * Returns the override value in the cache for the given group
+     *
+     * @param int $groupid group to get cached override data for
+     * @return ?\stdClass override value in the cache for the given group, or null if there is none.
+     */
+    public function get_cached_group_override(int $groupid): ?\stdClass {
+        $raw = $this->get_cache()->get($this->get_group_cache_key($groupid));
+        return empty($raw) || !is_object($raw) ? null : (object) $raw;
+    }
+
+    /**
+     * Returns the override value in the cache for the given user
+     *
+     * @param int $userid user to get cached override data for
+     * @return ?\stdClass the override value in the cache for the given user, or null if there is none.
+     */
+    public function get_cached_user_override(int $userid): ?\stdClass {
+        $raw = $this->get_cache()->get($this->get_user_cache_key($userid));
+        return empty($raw) || !is_object($raw) ? null : (object) $raw;
+    }
+
+    /**
+     * Deletes the cached override data for a given group
+     *
+     * @param int $groupid group to delete data for
+     */
+    public function clear_for_group(int $groupid): void {
+        $this->get_cache()->delete($this->get_group_cache_key($groupid));
+    }
+
+    /**
+     * Deletes the cached override data for the given user
+     *
+     * @param int $userid user to delete data for
+     */
+    public function clear_for_user(int $userid): void {
+        $this->get_cache()->delete($this->get_user_cache_key($userid));
+    }
+
+    /**
+     * Clears the cache for the given user and/or group.
+     *
+     * @param ?int $userid user to delete data for, or null.
+     * @param ?int $groupid group to delete data for, or null.
+     */
+    public function clear_for(?int $userid = null, ?int $groupid = null): void {
+        if (!empty($userid)) {
+            $this->clear_for_user($userid);
+        }
+
+        if (!empty($groupid)) {
+            $this->clear_for_group($groupid);
+        }
+    }
+}