MDL-17556: Improve performance of get_fast_modinfo when courses have many activities

course/lib.php

@@ -1088,15 +1088,8 @@ function &get_fast_modinfo(&$course, $userid=0) {
 
     $modlurals = array();
 
-    $cmids    = array();
-    $contexts = null;
-    foreach ($info as $mod) {
-        $cmids[$mod->cm] = $mod->cm;
-    }
-    if ($cmids) {
-        // preload all module contexts with one query
-        $contexts = get_context_instance(CONTEXT_MODULE, $cmids);
-    }
+    // If we haven't already preloaded contexts for the course, do it now
+    preload_course_contexts($course->id);
 
     foreach ($info as $mod) {
         if (empty($mod->name)) {
@@ -1128,11 +1121,14 @@ function &get_fast_modinfo(&$course, $userid=0) {
         }
         $cm->modplural = $modlurals[$cm->modname];
 
-        if (!$cm->visible and !has_capability('moodle/course:viewhiddenactivities', $contexts[$cm->id], $userid)) {
+        $modcontext = get_context_instance(CONTEXT_MODULE,$cm->id);
+
+        if (!$cm->visible and !has_capability('moodle/course:viewhiddenactivities', 
+            $modcontext, $userid)) {
             $cm->uservisible = false;
 
         } else if (!empty($CFG->enablegroupings) and !empty($cm->groupmembersonly)
-                and !has_capability('moodle/site:accessallgroups', $contexts[$cm->id], $userid)) {
+                and !has_capability('moodle/site:accessallgroups', $modcontext, $userid)) {
             if (is_null($modinfo->groups)) {
                 $modinfo->groups = groups_get_user_groups($course->id, $userid);
             }

course/view.php

@@ -39,6 +39,7 @@
         }
     }
 
+    preload_course_contexts($course->id);
     if (!$context = get_context_instance(CONTEXT_COURSE, $course->id)) {
         print_error('nocontext');
     }

lib/accesslib.php

@@ -2422,6 +2422,56 @@ function cleanup_contexts() {
     return true;
 }
 
+/**
+ * Preloads all contexts relating to a course: course, modules, and blocks.
+ *
+ * @param int $courseid Course ID
+ */
+function preload_course_contexts($courseid) {
+    global $context_cache, $context_cache_id, $CFG;
+
+    // Users can call this multiple times without doing any harm
+    static $preloadedcourses=array();
+    if(array_key_exists($courseid,$preloadedcourses)) {
+        return;
+    }
+
+    $rs=get_recordset_sql("
+SELECT 
+    x.instanceid, x.id, x.contextlevel, x.path, x.depth
+FROM 
+    {$CFG->prefix}course_modules cm
+    INNER JOIN {$CFG->prefix}context x ON x.instanceid=cm.id
+WHERE
+    cm.course={$courseid}
+    AND x.contextlevel=".CONTEXT_MODULE."
+UNION ALL
+SELECT 
+    x.instanceid, x.id, x.contextlevel, x.path, x.depth
+FROM 
+    {$CFG->prefix}block_instance bi
+    INNER JOIN {$CFG->prefix}context x ON x.instanceid=bi.id
+WHERE
+    bi.pageid={$courseid}
+    AND bi.pagetype='course-view'
+    AND x.contextlevel=".CONTEXT_BLOCK."
+UNION ALL
+SELECT 
+    x.instanceid, x.id, x.contextlevel, x.path, x.depth
+FROM 
+    {$CFG->prefix}context x
+WHERE
+    x.instanceid={$courseid}
+    AND x.contextlevel=".CONTEXT_COURSE."
+");
+    while($context=rs_fetch_next_record($rs)) {
+        $context_cache[$context->contextlevel][$context->instanceid] = $context;
+        $context_cache_id[$context->id] = $context;
+    }
+    rs_close($rs);
+    $preloadedcourses[$courseid]=true;
+}
+
 /**
  * Get the context instance as an object. This function will create the
  * context instance if it does not exist yet.