MDL-79930 mod_forum: Use MUC for forum count discussions

mod/forum/db/caches.php

@@ -32,4 +32,13 @@
         'simpledata' => true,
         'staticacceleration' => true
     ],
+    'forum_count_discussions' => [
+        'mode' => cache_store::MODE_REQUEST,
+        'simplekeys' => true,
+        'simpledata' => true,
+        'staticacceleration' => true,
+        'invalidationevents' => [
+            'changesinforumdiscussions',
+        ],
+    ],
 ];

mod/forum/lang/en/forum.php

@@ -62,6 +62,7 @@
 $string['blockperioddisabled'] = 'Don\'t block';
 $string['blogforum'] = 'Standard forum displayed in a blog-like format';
 $string['bynameondate'] = 'by {$a->name} - {$a->date}';
+$string['cachedef_forum_count_discussions'] = 'Forum discussions count';
 $string['cachedef_forum_is_tracked'] = 'Forum tracking status for user';
 $string['calendardue'] = '{$a} is due';
 $string['cancelreply'] = 'Cancel reply';

mod/forum/lib.php

@@ -1495,7 +1495,6 @@ function forum_count_discussion_replies($forumid, $forumsort = "", $limit = -1,
  * @global object
  * @global object
  * @global object
- * @staticvar array $cache
  * @param object $forum
  * @param object $cm
  * @param object $course
@@ -1504,13 +1503,21 @@ function forum_count_discussion_replies($forumid, $forumsort = "", $limit = -1,
 function forum_count_discussions($forum, $cm, $course) {
     global $CFG, $DB, $USER;
 
-    static $cache = array();
+    $cache = cache::make('mod_forum', 'forum_count_discussions');
+    $cachedcounts = $cache->get($course->id);
+    if ($cachedcounts === false) {
+        $cachedcounts = [];
+    }
 
     $now = floor(time() / 60) * 60; // DB Cache Friendly.
 
     $params = array($course->id);
 
-    if (!isset($cache[$course->id])) {
+    if (!isset($cachedcounts[$forum->id])) {
+        // Initialize the cachedcounts for this forum id to 0 by default. After the
+        // database query, if there are discussions then it should update the count.
+        $cachedcounts[$forum->id] = 0;
+
         if (!empty($CFG->forum_enabletimedposts)) {
             $timedsql = "AND d.timestart < ? AND (d.timeend = 0 OR d.timeend > ?)";
             $params[] = $now;
@@ -1528,26 +1535,24 @@ function forum_count_discussions($forum, $cm, $course) {
 
         if ($counts = $DB->get_records_sql($sql, $params)) {
             foreach ($counts as $count) {
-                $counts[$count->id] = $count->dcount;
+                $cachedcounts[$count->id] = $count->dcount;
             }
-            $cache[$course->id] = $counts;
+
+            $cache->set($course->id, $cachedcounts);
         } else {
-            $cache[$course->id] = array();
+            $cache->set($course->id, $cachedcounts);
+            return $cachedcounts[$forum->id];
         }
     }
 
-    if (empty($cache[$course->id][$forum->id])) {
-        return 0;
-    }
-
     $groupmode = groups_get_activity_groupmode($cm, $course);
 
     if ($groupmode != SEPARATEGROUPS) {
-        return $cache[$course->id][$forum->id];
+        return $cachedcounts[$forum->id];
     }
 
     if (has_capability('moodle/site:accessallgroups', context_module::instance($cm->id))) {
-        return $cache[$course->id][$forum->id];
+        return $cachedcounts[$forum->id];
     }
 
     require_once($CFG->dirroot.'/course/lib.php');
@@ -3113,6 +3118,9 @@ function forum_add_discussion($discussion, $mform=null, $unused=null, $userid=nu
         forum_trigger_content_uploaded_event($post, $cm, 'forum_add_discussion');
     }
 
+    // Clear the discussion count cache just in case it's in the same request.
+    \cache_helper::purge_by_event('changesinforumdiscussions');
+
     return $post->discussion;
 }
 
@@ -3173,6 +3181,9 @@ function forum_delete_discussion($discussion, $fulldelete, $course, $cm, $forum)
     $event->add_record_snapshot('forum_discussions', $discussion);
     $event->trigger();
 
+    // Clear the discussion count cache just in case it's in the same request.
+    \cache_helper::purge_by_event('changesinforumdiscussions');
+
     return $result;
 }
 

mod/forum/tests/lib_test.php

@@ -4291,4 +4291,87 @@ public function test_forum_check_throttling_student() {
         $this->assertIsObject($throttling);
         $this->assertFalse($throttling->canpost);
     }
+
+    /**
+     * Tests forum_count_discussions.
+     *
+     * @covers ::forum_count_discussions
+     */
+    public function test_forum_count_discussions(): void {
+        $this->resetAfterTest();
+
+        $generator = $this->getDataGenerator();
+        $forumgenerator = $generator->get_plugin_generator('mod_forum');
+        $course1 = $generator->create_course();
+        $course2 = $generator->create_course();
+        $student = $generator->create_user(['trackforums' => 1]);
+
+        // First forum.
+        $forumobj1 = new \stdClass();
+        $forumobj1->introformat = FORMAT_HTML;
+        $forumobj1->course = $course1->id;
+        $forumobj1->trackingtype = FORUM_TRACKING_FORCED;
+        $forum1 = $generator->create_module('forum', $forumobj1);
+        $forum1cm = get_coursemodule_from_id('forum', $forum1->cmid, 0, false, MUST_EXIST);
+
+        // Second forum.
+        $forumobj2 = new \stdClass();
+        $forumobj2->introformat = FORMAT_HTML;
+        $forumobj2->course = $course2->id;
+        $forumobj2->trackingtype = FORUM_TRACKING_OFF;
+        $forum2 = $generator->create_module('forum', $forumobj2);
+        $forum2cm = get_coursemodule_from_id('forum', $forum2->cmid, 0, false, MUST_EXIST);
+
+        // Third forum.
+        $forumobj3 = new \stdClass();
+        $forumobj3->introformat = FORMAT_HTML;
+        $forumobj3->course = $course2->id;
+        $forumobj3->trackingtype = FORUM_TRACKING_OFF;
+        $forum3 = $generator->create_module('forum', $forumobj3);
+        $forum3cm = get_coursemodule_from_id('forum', $forum3->cmid, 0, false, MUST_EXIST);
+
+        // First make sure there are no discussions for any of the forums.
+        $f1discussionscount = forum_count_discussions($forum1, $forum1cm, $course1);
+        $this->assertEquals(0, $f1discussionscount);
+        $f2discussionscount = forum_count_discussions($forum2, $forum2cm, $course2);
+        $this->assertEquals(0, $f2discussionscount);
+        $f3discussionscount = forum_count_discussions($forum3, $forum3cm, $course2);
+        $this->assertEquals(0, $f3discussionscount);
+
+        // Add 3 discussions to forum 1.
+        $discussionobj1 = new \stdClass();
+        $discussionobj1->course = $course1->id;
+        $discussionobj1->userid = $student->id;
+        $discussionobj1->forum = $forum1->id;
+        $forumgenerator->create_discussion($discussionobj1);
+        $forumgenerator->create_discussion($discussionobj1);
+        $forumgenerator->create_discussion($discussionobj1);
+
+        // Make sure there are 3 discussions.
+        $f1discussionscount = forum_count_discussions($forum1, $forum1cm, $course1);
+        $this->assertEquals(3, $f1discussionscount);
+
+        // Add 4 discussions to forum 2.
+        $discussionobj2 = new \stdClass();
+        $discussionobj2->course = $course2->id;
+        $discussionobj2->userid = $student->id;
+        $discussionobj2->forum = $forum2->id;
+        $forumgenerator->create_discussion($discussionobj2);
+        $forumgenerator->create_discussion($discussionobj2);
+        $forumgenerator->create_discussion($discussionobj2);
+        $discussion24 = $forumgenerator->create_discussion($discussionobj2);
+
+        // Make sure there are 4 discussions.
+        $f2discussionscount = forum_count_discussions($forum2, $forum2cm, $course2);
+        $this->assertEquals(4, $f2discussionscount);
+
+        // Delete one discussion from forum 2.
+        forum_delete_discussion($discussion24, true, $course2, $forum2cm, $forum2);
+        $f2discussionscount = forum_count_discussions($forum2, $forum2cm, $course2);
+        $this->assertEquals(3, $f2discussionscount);
+
+        // Make sure there are no discussions.
+        $f3discussionscount = forum_count_discussions($forum3, $forum3cm, $course2);
+        $this->assertEquals(0, $f3discussionscount);
+    }
 }

mod/forum/version.php

@@ -24,6 +24,6 @@
 
 defined('MOODLE_INTERNAL') || die();
 
-$plugin->version   = 2023100900;       // The current module version (Date: YYYYMMDDXX).
+$plugin->version   = 2023100901;       // The current module version (Date: YYYYMMDDXX).
 $plugin->requires  = 2023100400;       // Requires this Moodle version.
 $plugin->component = 'mod_forum';      // Full name of the plugin (used for diagnostics)