MDL-45466 forum: performance improvement for mass (un)subscriptions

mod/forum/classes/observer.php

@@ -86,8 +86,9 @@ public static function role_assigned(\core\event\role_assigned $event) {
         $forums = $DB->get_records_sql($sql, $params);
         foreach ($forums as $forum) {
             // If user doesn't have allowforcesubscribe capability then don't subscribe.
-            if (has_capability('mod/forum:allowforcesubscribe', context_module::instance($forum->cmid), $userid)) {
-                forum_subscribe($userid, $forum->id);
+            $modcontext = context_module::instance($forum->cmid);
+            if (has_capability('mod/forum:allowforcesubscribe', $modcontext, $userid)) {
+                forum_subscribe($userid, $forum->id, $modcontext);
             }
         }
     }

mod/forum/index.php

@@ -193,9 +193,9 @@
         if (!forum_is_forcesubscribed($forum)) {
             $subscribed = forum_is_subscribed($USER->id, $forum);
             if ((has_capability('moodle/course:manageactivities', $coursecontext, $USER->id) || $forum->forcesubscribe != FORUM_DISALLOWSUBSCRIBE) && $subscribe && !$subscribed && $cansub) {
-                forum_subscribe($USER->id, $forumid);
+                forum_subscribe($USER->id, $forumid, $modcontext);
             } else if (!$subscribe && $subscribed) {
-                forum_unsubscribe($USER->id, $forumid);
+                forum_unsubscribe($USER->id, $forumid, $modcontext);
             }
         }
     }

mod/forum/lib.php

@@ -143,7 +143,7 @@ function forum_instance_created($context, $forum) {
     if ($forum->forcesubscribe == FORUM_INITIALSUBSCRIBE) {
         $users = forum_get_potential_subscribers($context, 0, 'u.id, u.email');
         foreach ($users as $user) {
-            forum_subscribe($user->id, $forum->id);
+            forum_subscribe($user->id, $forum->id, $context);
         }
     }
 }
@@ -241,7 +241,7 @@ function forum_update_instance($forum, $mform) {
     if (($forum->forcesubscribe == FORUM_INITIALSUBSCRIBE) && ($oldforum->forcesubscribe <> $forum->forcesubscribe)) {
         $users = forum_get_potential_subscribers($modcontext, 0, 'u.id, u.email', '');
         foreach ($users as $user) {
-            forum_subscribe($user->id, $forum->id);
+            forum_subscribe($user->id, $forum->id, $modcontext);
         }
     }
 
@@ -4819,12 +4819,12 @@ function forum_get_optional_subscribed_forums() {
 /**
  * Adds user to the subscriber list
  *
- * @global object
  * @param int $userid
  * @param int $forumid
+ * @param context_module|null $context Module context, may be omitted if not known or if called for the current module set in page.
  */
-function forum_subscribe($userid, $forumid) {
-    global $DB;
+function forum_subscribe($userid, $forumid, $context = null) {
+    global $DB, $PAGE;
 
     if ($DB->record_exists("forum_subscriptions", array("userid"=>$userid, "forum"=>$forumid))) {
         return true;
@@ -4836,9 +4836,18 @@ function forum_subscribe($userid, $forumid) {
 
     $result = $DB->insert_record("forum_subscriptions", $sub);
 
-    $cm = get_coursemodule_from_instance('forum', $forumid);
+    if (!$context) {
+        // Find out forum context. First try to take current page context to save on DB query.
+        if ($PAGE->cm && $PAGE->cm->modname === 'forum' && $PAGE->cm->instance == $forumid
+                && $PAGE->context->contextlevel == CONTEXT_MODULE && $PAGE->context->instanceid == $PAGE->cm->id) {
+            $context = $PAGE->context;
+        } else {
+            $cm = get_coursemodule_from_instance('forum', $forumid);
+            $context = context_module::instance($cm->id);
+        }
+    }
     $params = array(
-        'context' => context_module::instance($cm->id),
+        'context' => $context,
         'objectid' => $result,
         'relateduserid' => $userid,
         'other' => array('forumid' => $forumid),
@@ -4853,21 +4862,30 @@ function forum_subscribe($userid, $forumid) {
 /**
  * Removes user from the subscriber list
  *
- * @global object
  * @param int $userid
  * @param int $forumid
+ * @param context_module|null $context Module context, may be omitted if not known or if called for the current module set in page.
  */
-function forum_unsubscribe($userid, $forumid) {
-    global $DB;
+function forum_unsubscribe($userid, $forumid, $context = null) {
+    global $DB, $PAGE;
 
     $DB->delete_records('forum_digests', array('userid' => $userid, 'forum' => $forumid));
 
     if ($forumsubscription = $DB->get_record('forum_subscriptions', array('userid' => $userid, 'forum' => $forumid))) {
         $DB->delete_records('forum_subscriptions', array('id' => $forumsubscription->id));
 
-        $cm = get_coursemodule_from_instance('forum', $forumid);
+        if (!$context) {
+            // Find out forum context. First try to take current page context to save on DB query.
+            if ($PAGE->cm && $PAGE->cm->modname === 'forum' && $PAGE->cm->instance == $forumid
+                    && $PAGE->context->contextlevel == CONTEXT_MODULE && $PAGE->context->instanceid == $PAGE->cm->id) {
+                $context = $PAGE->context;
+            } else {
+                $cm = get_coursemodule_from_instance('forum', $forumid);
+                $context = context_module::instance($cm->id);
+            }
+        }
         $params = array(
-            'context' => context_module::instance($cm->id),
+            'context' => $context,
             'objectid' => $forumsubscription->id,
             'relateduserid' => $userid,
             'other' => array('forumid' => $forumid),

mod/forum/unsubscribeall.php

@@ -50,7 +50,7 @@
     $forums = forum_get_optional_subscribed_forums();
 
     foreach($forums as $forum) {
-        forum_unsubscribe($USER->id, $forum->id);
+        forum_unsubscribe($USER->id, $forum->id, context_module::instance($forum->cm));
     }
     $DB->set_field('user', 'autosubscribe', 0, array('id'=>$USER->id));